> how people wrap their head around multiple changes in multiple features at the same time?

Long before AI I routinely had 5 parallel development environments I would flip between. (I do distributed systems stuff, think HPC-adjacent clusters, when you're too big for Kubernetes and too small for supercomputing). One would be running long-running tests for my current changes, one being reset to a clean state, and 3 more on standby so I had 100% "duty cycle" (the reset took a while). You got used to multitasking.

Its different though, because your tasks were long-running and you are forced to have idle time between those runs.

In case of AI, it just delivers things in 2-3 minutes, this time is not enough (or worth) to switch the context (for me personally)