how far does a safety shot have to be? can very serious games get into stalemates where each player only wants to move the cue and object balls slightly?

thanks in advance! and i'm asking for serious type money games. obviously fun at the bar i personally wouldn't do safety shots without moving either the cue or object ball quite significantly. in fact, in friendly game, i'd probably try to make a shot or advance a ball offensively at same time i'd be thinking safety shot i.e. i wouldn't do a pure safety shot. $$$$$ is completely different though

now that i've googled (without success), i think my terminology by end of my original post might have be wrong. i meant i'd try to advance/make my own ball while making things difficult for opponent. i think that safety shot might mean that you are calling no shot going in (although that makes no sense, i'm thinking..... might as well call something - right?)

This is from the WPBA rules:

Multiple Safes – After 4 consecutive safes are executed (2 by each player) where the object is being bumped to the same rail and the cue ball strikes no rail after contact with the object ball in each safe, on the next (5th) shot, the object ball or legally struck numbered ball must be driven to another rail or the cue ball must contact a rail after contact with the object ball. Failure to execute the described legal shot on the 5th attempt will be a foul. The opponent must declare to the player at the table that they are on 4 consecutive safes, and the player must acknowledge. If a foul occurs, the opponent receives ball in hand.

thanks very much!!.... going to shoot pool this afternoon......... strange but it seems just after i started playing again, that tsn and maybe other canadian networks have started showing alot of pool.