Thanks to everyone for their reasons, however, it seems clear to me that unnecessary chalking is truly a conscious or unconscious crutch. It appears that the shooter lacks confidence to only chalk once before shooting. The shooter does not need to justify standing up to reexamine the situation. The shooter should be confident and brave enough to only chalk at most once per shot. Most shooters seen to have been trapped into slavishly following a mindless pre-shot routine advocated by others rather than thinking for themselves. That's the difference between a leader and a follower. Sorry if this offends most players, but that is how I see it.