I don't leave the floor until its safe to brace it with at least a 1-3" brace. Otherwise everything I see on a long string is pretty much false, that's my way of doing.
With you Drums, I gave up the long string a while back for several reasons, namely the LSL (long string lie). Now if you anticipate and work with it like Pat does, that's fine, but you gotta be able to read it. I typically floor tiller til I slap a string on her that get's a 1" brace or lays taut on the belly, whatever kind of ends up happening, and go from there. The last one I did I actually went for a 3" brace. I feel like I waste less time like this, personally.