Let’s start with the baked potatoes. If a cookbook said:

-Preheat oven
-Insert potatoes
-Stare at potatoes with undivided attention while they cook for 1 hr
-Serve potatoes

I doubt the cookbook would sell well. This is an example of estimator incompetence. Or is it?

Constant operator input isn’t required while the potatoes are baking. However, some level of operator attention is. This is where the ambiguity comes into play. “Time” can have multiple meanings. There is calendar time and effort time. Let’s say the calendar time for the potatoes is 1 hour. The effort expended may be a total of 1 minute across that hour.

Now, bring in the phone call while the potatoes are baking. Yes, there is no need to watch the potatoes cook 100% of the time. However, there is the need to make sure they aren’t forgotten (effort).

One thing that happens with multitasking is something occurs which wasn’t expected and attention narrows down to the event at hand. If that occurs the potatoes are at risk for over-cooking.Yes, alarms can be set, etc., but if the distraction is great enough or takes the person away from the task running in background there is the chance of forgetting about the potatoes cooking. Speaking as a parent, imagine you have a 2 year old who has wandered away (while your wife is preoccupied with getting the twice-baked potatoes just right before putting them back in the oven) and a blood-curdling scream comes from a remote part of the house. The potatoes will probably be forgotten.

In project management terms we are talking about the intersection between schedule float and risk. Float is time between tasks that is completely free. With the potatoes some attention is needed. So, technically, there isn’t float available across the entire task. There is float available between check-ins. If float is assumed across the entire cooking time without check-ins a risk calculation must be performed and a strategy initiated. Ignoring this reality hammers a lot of PMs and SMEs. Ever start a download you assumed was running okay and come back an hour later to find some small issue had stopped it 3 minutes into the download? Here, the operator confused the need for a little effort (checking in) with zero effort and eliminated the risk associated with multitasking. This occurs with estimates as well. The coordinated check-ins across multiple efforts are significant but can be so small they are considered to have zero duration. The estimate can turn into a house of cards.

So what about pumping gas and washing one’s windshield simultaneously. Multitasking, as stated in the blog, can occur with highly repetitive tasks, e.g., washing a car window. So, the thesis in the blog holds if there is another no-brainer task being performed. But, let’s look closer at the situation.

Gas stations where I live have almost all done one of two things:
-put a sign up that says do not leave the pump handle while filling your tank, or;
-removed the clip that holds the handle in the fill position so one doesn’t have to squeeze it while filling up.

Why do this? Multitasking risks creating an unstable situation. Operator attention is needed. So, while one can wash their windshield there is a degree of risk. Personally, I’ve seen more than one car overflow when the person walks away.
Overall, I am talking about the intersection between definitions of time, risk, and schedule management. In other words, for highly-repetitive, zero-risk tasks multitasking is okay. For the really deep stuff, and some of the shallower, attempting to multitasking is dangerous and impossible. Micro-bookmarking, yes. Multitasking, no. Walking and chewing gum, however, is okay.

Let’s start with the baked potatoes. If a cookbook said:

-Preheat oven
-Insert potatoes
-Stare at potatoes with undivided attention while they cook for 1 hr
-Serve potatoes

I doubt the cookbook would sell well. This is an example of estimator incompetence. Or is it?

Constant operator input isn’t required while the potatoes are baking. However, some level of operator attention is. This is where the ambiguity comes into play. “Time” can have multiple meanings. There is calendar time and effort time. Let’s say the calendar time for the potatoes is 1 hour. The effort expended may be a total of 1 minute across that hour.

Now, bring in the phone call while the potatoes are baking. Yes, there is no need to watch the potatoes cook 100% of the time. However, there is the need to make sure they aren’t forgotten (effort).

One thing that happens with multitasking is something occurs which wasn’t expected and attention narrows down to the event at hand. If that occurs the potatoes are at risk for over-cooking.Yes, alarms can be set, etc., but if the distraction is great enough or takes the person away from the task running in background there is the chance of forgetting about the potatoes cooking. Speaking as a parent, imagine you have a 2 year old who has wandered away (while your wife is preoccupied with getting the twice-baked potatoes just right before putting them back in the oven) and a blood-curdling scream comes from a remote part of the house. The potatoes will probably be forgotten.

In project management terms we are talking about the intersection between schedule float and risk. Float is time between tasks that is completely free. With the potatoes some attention is needed. So, technically, there isn’t float available across the entire task. There is float available between check-ins. If float is assumed across the entire cooking time without check-ins a risk calculation must be performed and a strategy initiated. Ignoring this reality hammers a lot of PMs and SMEs. Ever start a download you assumed was running okay and come back an hour later to find some small issue had stopped it 3 minutes into the download? Here, the operator confused the need for a little effort (checking in) with zero effort and eliminated the risk associated with multitasking. This occurs with estimates as well. The coordinated check-ins across multiple efforts are significant but can be so small they are considered to have zero duration. The estimate can turn into a house of cards.

So what about pumping gas and washing one’s windshield simultaneously. Multitasking, as stated in the blog, can occur with highly repetitive tasks, e.g., washing a car window. So, the thesis in the blog holds if there is another no-brainer task being performed. But, let’s look closer at the situation.

Gas stations where I live have almost all done one of two things:
-put a sign up that says do not leave the pump handle while filling your tank, or;
-removed the clip that holds the handle in the fill position so one doesn’t have to squeeze it while filling up.

Why do this? Multitasking risks creating an unstable situation. Operator attention is needed. So, while one can wash their windshield there is a degree of risk. Personally, I’ve seen more than one car overflow when the person walks away.
Overall, I am talking about the intersection between definitions of time, risk, and schedule management. In other words, for highly-repetitive, zero-risk tasks multitasking is okay. For the really deep stuff, and some of the shallower, attempting to multitasking is dangerous and impossible. Micro-bookmarking, yes. Multitasking, no. Walking and chewing gum, however, is okay.

1. Whoever did the estimating is incompetent, or;
2. Whoever is doing the work has been sandbagging and holding back capabilities.”

Most people that I know multitask because their tasks allow for efficient usage of their time by multitasking. for instance, I clean my car's windshield while the gas is pumping.. my wife makes a phone call while the potatoes are baking.Neither of us is incompetent or sandbagging — the task in hand has “wait” built-in and that's why we are able to multitask. None of your assumptions apply in our case.