You made sense but, if you can set a flag in the loop, you can also call a subroutine in the same place as you were setting the flag, and the subroutine can do what ever you would have done as a result of the flag being set after the loop, so your back to square one.

That's not to say that there aren't occasions when a flag is necessary, or even just easier, but most times they can be avoided and the code benefits from their avoidance.