You start recording the moment you arrive at the scene
(if not earlier)
And stop recording once you're far away from the scene
The benefit is obvious: you're always ready to capture those rare & spontaneous moments that create great cinema.
The biggest challenge is actually the amount of material captured.
It can easily feel overwhelming having to log so many hours of footage.
I wish I had something better to say about it.
But the fact is that somebody needs to log all of the footage - either you or the editor.
Understandably, there'll be times when luxuriating over all of the footage is not possible...