As for dropping a bean bag if K steps out of bounds and then re-establishes before contact/recovery, he's already fouled so you should drop a flag rather than a bean bag.
Perhaps something that applies only to certain section of Rome, but the lesson was: A beanbag is a tool, to help pinpoint a particular spot that may (or may not) be subsequently important, that circumstances prevent you from Staying at while play continues. As for identifying a spot where someone went OOB, it's not absolutely necessary EXCEPT where their may be a subsequent dispute, about that spot, or if the player actually stepped OOB.
Like, "an ounce of prevention is worth a pound of cure", a beanbag on a previous OOB designation can eliminate a lot of meaningless BS. When it proves to be unnecessary, it's simply picked up. If it might be kicked, or otherwise moved, it's simply not helpful.
A Flag is a whole different matter, and often having that beanbag to support why it was thrown can be very helpful.