Multi-tasking - Island of Sanity

Island of Sanity



Economics

Multi-tasking


Multi-tasking versus Single-Threading

Any time I've looked for a job, one requirement that employers consistently ask for is "ability to multi-task". Suck up that I am, I always enthusiastically say, "Oh yes, I can do that." But I think a much better answer would be, "I can when necessary, but I try not to." Multi-tasking is inherently inefficient."

(Side note to my present employer if he happens to read this: No, I am not looking for another job. I'm very happy here.)

In many companies, if an employee has more than one project to work on, he is expected to work on these projects simultaneously. That is, if he has 40 hours in a week and 3 projects, he should devote about 13 1/3 hours to each. I think the better approach would be to pick one project and work it to completion, then do the second, then do the third.

There are at least two problems with multi-tasking.

Shifting Gears

First, it takes time to switch from one project to another. Depending on what sort of project it is, you may have to put away one set of tools and take out another, shut down one piece of equipment and start up another, or put away one set of files and open up another. You may have to go to a different room or a different building. At the very least, you have to shift your thinking, get the issues for project A out of your head and start thinking about project B. You have to remember where you left off and what you were doing.

How long switching gears takes depends on what sort of job you have and what sort of projects you're working on. In some cases the physical process might be as simple as putting one folder back in a drawer and taking out another. In other cases it might involve travelling to another city. You might be thinking, "Hey, in my job it's no big deal. I just close one Word document and open the other. It's a couple of seconds." But is it really? Evan at that, you probably have to navigate around directories to find the other file. If it's been a couple of days since you worked on it you may have forgotten where it is and have to look for it. Then you open the file and you have to find the place where you left off. But more important, then you have to remember what you had finished last time and what was still to be done. This often means reading over the text to say, "Oh yeah, I got the cost figures in and I was just starting on the staffing requirements" or whatever. I almost never switch between two tasks in seconds. It's always at least a few minutes, sometimes substantial amounts of time.

Suppose you have three jobs that would each take, whatever, say 200 hours each if you did them one at a time. If you spend 8 hours per day on project A until it's done and then spend 8 hours per day on project B until it's done, and then 8 hours per day on project C until it's done, then you'll finish all three in 600 hours or 75 working days. But if you try to spend one third of your time each day on each project, there's going to be some extra time in there to shift gears. Suppose it takes you just 15 extra minutes to switch tasks. You have to do this twice per day. Then each day you're spending 30 minutes shifting gears and only 7 hours and 30 minutes on productive work, and it will take 80 days to complete all three projects. You've added a week to the total time.

Delivery Dates

Presumably the point of doing any of these projects is that they give some benefit to the company, its customers, or its employees. Often there's no benefit until the project is completed. A car with two of the four wheels installed is not half as useful as one with all four wheels; it's worth pretty much zero until it's complete.

So let's say that you have three projects to work on, A, B, and C. Each will take one month of work to complete. Let's ignore the shifting-gears issue and suppose that there is zero change-over time. Let's suppose, just to make up a number, that each project produces $10,000 per month in benefits once completed.

If you work on all three projects simultaneously, then you will finish all three on the final day of the third month.

Suppose instead you work on project A until it's done, then work on project B, then work on project C. Then you will finish project A at the end of the first month, project B at the end of the second month, and project C at the end of the third month.

SO under the multi-tasking plan, there is zero benefit in month 1 (you're working on all three projects), zero benefit in month 2 (still working), zero benefit in month 3 (still working), and then $30,000 benefit in month 4 (all 3 done).

Under the single-threading plan, there is zero benefit in month 1 (working on project A), $10,000 benefit in month 2 (A is done, working on B), $20,000 benefit in month 3 (A and B are done, working on C), and $30,000 in month 4 (all 3 done). That is, by single threading, you get the benefits of project A two months earlier and the benefits of project B one month earlier. In this example, you get an extra $30,000.

Caveats

There are sometimes reasons why you have to multi-task. Sometimes you reach a point in a project where you have to wait on someone else. You might have to wait for parts or supplies to be delivered, or for a co-worker to do a task that he has been assigned. At that point you might as well put that project aside and work on something else until you can get back to it.

Sometimes there are political reasons why you have to do things in less than the most efficient manner. If you have three projects to work on, then even if it would be more efficient to do one at a time, it may be that customers are demanding regular progress reports and you can't just tell them "we'll get to your project in two months".

The better plan

But in general, you're far better off to follow this plan: Identify the most important or productive thing you have to do. Work on that until you finish it, or you reach a point where you can't work on it any more because of outside factors. Then move to the next most important thing. Etc.

© 2020 by Jay Johansen


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