I know exactly what you mean, and had many a discussion with it with Paul over the years.
We also found that there were (less) times when starting out on a journey - stopping and then found a more enlighten approach.
So what we tried and found usually (more often than not) worked was to stop, take 5, relax and just start a 'new' journey as it were. That had more effect of a reset than anything else.
How it worked we never fully worked out for sure.
Obviously there is the obvious break and the psychological effects that can have. Whether it 'resets' the brain in any more of a fundamental way I dunno.
I have rarely experienced it not working, and at worst retained the 'same' useless ability.
We tried to figure on previous days work load - figuring if a 'tired' level was at play, but it didn't seem to be that constant.
If I have it happen I relax take a 10% more in my safety margins and ensure that I am on a high alert / anticipation status. This can in itself 'resolve it', you just slip back into the full on capability mode. HTH.