@oleskool830 jelly is right on all points in his response.
The reason i do the crushing over a bit wider area is its a more gentle curve and relieves stress in comparison to a sharp bend which may break the stem.
posted this pic elsewhere but its literally what happens to our stems usually a combinations of all.
As for the "Flopping" terminology really its just supercropping with some slight adjustments and possible added LST till things set in place.
I just prefer the term, as its literally what your doing "flopping tops"
And three weeks is fine, its later in flower where the plants won't recover as quickly such as say 6+ weeks in on a 9 week strain the stem does not recover as quick and there is usually some decent weight forming so bonus helps them stay down, but you may get a sideways bud that starts reaching upwards as its growing out but up at the same time.
think a wind swept tree for example, just watch out for the balance of the plant obviously, the big plant i cut last night if the coco was dry and the big bud wasn't resting against something would of fallen over in a heart beat, which it did twice while i was taking photos and trimming, so the big bud got chopped first.