One of the worst unspoken bits is the cognitive load associated with such long running things, e.g compile or CI, which ideally are successful but that's not always the case, so you're doing something else while - consciously or not - anxiously waiting for the other thing to complete.
And when - when! - that job fails, you can be pretty sure it racks up some cortisol as one has to interrupt†your second task, pop back to the original context, curse at oneself for forgetting that comma or whatever simple thing, rerun, rinse, and repeat.
†The alternative is to finish (or reach a checkpoint) your other task, but that has cumulative latency effects on the duration of that other task that is supposed to be your main one.
And when - when! - that job fails, you can be pretty sure it racks up some cortisol as one has to interrupt†your second task, pop back to the original context, curse at oneself for forgetting that comma or whatever simple thing, rerun, rinse, and repeat.
†The alternative is to finish (or reach a checkpoint) your other task, but that has cumulative latency effects on the duration of that other task that is supposed to be your main one.