> low priority stuff to do for a bit (or a high priority short task that interrupts) seems to let my subconscious solve the issue in the background and keeps me happier and more motivated.

For a bit is ok. I had one month task, that was interrupted daily for over a year, that's how I got demotivated and burned out so much that I needed neurologist.

> two difficult tasks that were supposed to be done in parallel maybe that would be different, but I've never seen anyone asking for that.

Probably that's why you say interruptions are good, no experience of how bad can interruptions be.

But if that person has rare skills where at least 25% of their output makes another team of 5 100% more effective (200%), than than loss of 50% output is actually a 33% gain in output!

Say you have a team of 6 (5+1 DevOps Wizard), and a team of 5. so Call it 5x200 +5 x100% output, 1500 output total. Split our wizard in half and you get 5x200 + 5x200 = 2000 output total!

At a certain minimum level the effectiveness inverts because people are waiting on wizard magic and everyone is less effective, but there is benefit to having specialists be split.

It's funny, because LLMs have context switching costs too! Cached tokens cost less than non-cached. There's no reason to think that doesn't apply to humans.

I’ve genuinely found that context switching is a skill like any other. When I first started using LLMs and context switching doing 5-10 different work streams at once I was utterly, utterly exhausted at the end of each day.

Now many months in, it doesn’t feel nearly as taxing.

Maybe this is in no small part due to LLMs improving enough you don’t have to spend as much mental energy reviewing their output and them being better at managing worktrees and other tedium, but the idea of doing lots of things at once feels like a mental muscle that was previously weak and has gained in strength in ways I never though possible for me.

I am friendly with a project manager at work - he's overseeing a fairly big modernisation project with lots of stakeholders, lots of moving parts, lots of direct reports, and while he seems to have a lot of long lunches, he makes sure that no one working on the project is blocked - he'll do everything he needs to to unblock people - regular meetings to hear about blockers, chase down approvers, just tell his direct reports to do something without approval (as long as it's not something bad) and he'll deal with the consequences. But most people are not this dedicated unfortunately.

Single Piece Flow fits with other Toyota ideas of how to get high quality work done. If something is frequently blocking the line, the solution is to put resources toward the bottleneck, not spin up more work in parallel.

Projects can be broken down into parallel pieces of work, so you should always be able to pick up another part of the project rather than switch to a different project if you're blocked. As the other poster says, the goal is to not be blocked though. The leadership team need to support the delivery team to get the work done as a focused flow of items with as little blocking and waiting time as possible. If you're getting blocked, that's a signal that the org is failing.

Admittedly this is a little idealistic, but if it's not the goal then the reality is always far worse.