I read a couple of articles recently and can now distill the vague feeling that I've always had that multi-tasking is not a good thing down to a simple statement that it is certainly a very bad thing.
And I can prove it.
Watch, nothing up my sleeve...
We all know there's thrash when switching, but let's assume that you've got some kind of dream team that can switch tasks perfectly. I do this because I don't want to get into a long discussion of "how good I am at multi-tasking".
Suppose we have 4 projects of 6 months duration each. Let's have the team multi-task and do all those things in parallel. They work one month on Project 1 , then move on to Project 2, and so on. Since there's no thrash it shouldn't hurt much right?
The average time to complete the projects is 22.5 months or just short of two years.
Now let's have our same team concentrate on one project at a time and see what happens.
This time the average time to complete is 15 months. That's 2/3 of the average for the multi-tasking schedule. But wait... it gets worse. What if those four projects are not of equal value.
We know that all projects are not created equal. Some are more valuable to your business than others. It is quite possible that your highest value project is a factor of ten more valuable than your least valuable project (or more). Let's model this by saying that each project on our stack-ranked list is twice as valuable as the one below it. Remember, I'm talking value not effort here.
Let's look 30 months out and see what each method has delivered in value to the business. Here's what the plots look like when the vertical scale is business value per month. The light green shaded area is the total value the projects have generated 30 months after project initiation.
So the multi-tasking project management method has delivered 124 units of value (8*9 + 4*8 + 2*7 + 1*6 = 124). But the single-tasking project... whoa... look out!
That's a whopping 294 units of value (8*24 + 4*18 + 2*12 + 1*6). More than DOUBLE.
In other words, if I worked for Single-Tasking Enterprises and you worked for Multi-Tasking Incorporated we'd be kicking your ass. (And no, you wouldn't be an acquisition target since we don't want your crappy multi-tasking IP.)
Okay, so multi-tasking sucks. What can you do about it?
I think the most important thing is to work off of a single prioritized list. You need one single list stacked top to bottom by priority for your people to use. The list must be public within your company. That way everyone is on the same page as to which project gets worked on first.
But I can hear you saying, "Hey, we work on many things at once because we're so busy and need to get all this stuff done yesterday!"
Yeah, and you can keep doing that. And as I've shown it will keep killing your business.
As leaders (and I mean anyone who has people under them) we must set hard priorities and stick to them. Constant switching of a person's "top priority" is a sure sign of weakness as a leader. If you are doing this STOP.
But what if you made a mistake in the priority order?
Look, even if we reverse the business value order and deliver the lowest value projects first we still come out ahead single-tasking. We get 156 units of value at the 30 month mark (1*24 + 2*18 + 4*12 + 8*6). That's still 25% more than the multi-tasking result with the "proper order".
The lesson is that it is less important that you pick exactly the optimal order in which to do projects. It is critically important that you build teams that focus on delivering one project at a time. Your teams must be empowered to protect their time and their schedule by telling all distractions to "piss directly off". Your leads must understand this and be rewarded for protecting their folks from distractions.
I find this stuff fascinating. How could I have run projects for all these years and never noticed how bad this is before?