Multitask repetitive or time consuming tasks only. When I was in college I worked for a mom and pop type PC repair store.

Doing PC re-imaging, I set up 6 stations and would kick off one refresh and while it was running, start up the next one and so on. Using disks to install took ages, so I figured out how to make bootable USB sticks, so I would have all 6 or occasionally more (by stealing bench seats) stations humming away while I was also doing part upgrades or builds on another station, only pausing to check up on progress.

That is ideal multitasking, where you need to pay a small amount of attention to one arduous group of tasks and the remainder of your time is free to focus on fine detail high mental demand tasks with ease.

What you described is pipelining. [0] [1] Pipelining depends on some tasks being inherently parallelizable.

[0] https://en.wikipedia.org/wiki/Pipeline_(computing) [1] https://cs.stanford.edu/people/eroberts/courses/soco/project...

Well you were still concentrating on one task only: setting up computers. :)

it makes sense if you read it as: I'm working at 80% of my capacity for 20% of the time, I get 16% of my possible productivity

Right. It feels like Op uses wrong math but gets a good conclusion in the context of doing daily job: focus on one shit.

However, in general sense, the return of an investment is considered as random variable, so the problem is not just max value, but max value while minimizing risk, and the solution is multitask/portfolio

Your comment helps me. I think I'm getting closer to the mechanism of what causes me to procrastinate. When many tasks are due, all important but of tiny ROI, like washing dishes and vacuuming, I feel overwhelmed because my mind can't sort them by expected reward.

I also noticed that I engage in extreme procrastination when the rewards of a high effort task are uncertain. It's like my body recoils at the idea of expending energy unnecessarily. For example, creating a "portfolio-worthy side project" immediately queues up questions, "But I heard recruiters don't look at them. If they do they'll look at it for a second. What if they think my code sucks and I blow myself out instead?" Etc etc

If anyone has some sort of mental model or frame which they're conscious of in these situations, I would love to hear it. I started researching CBT for ADHD last night and now I have 30 tabs of research articles, infographics, blog posts, book reviews and god damn it if I didnt go and get stuck in Wikipedia instead...

Unless you consider the result of two tasks performed simultaneously a product of two tasks rather than the sum of two tasks.

+1. Your 0.1 estimate is an underestimate. Context switching is a very costly if I'm balls deep in a bug fix where I already need to care about 10 thinks. When I go back it's very easy to miss out on something which makes my productivity 0 because you introduced a new bug while fixing the older one lol.

I'd gauge making a mistake which must later be debugged as negative productivity