I have an almost unbounded willingness to let players bet what they want. I have little tolerance for angle shooting, though. I don't like betting lines. I don't like forward motion rules. I do like teaching players saying what you intend to do will prevent all sorts of trouble. We aren't playing chess with finger fault rules (once you touch a piece, you have to move it.)
It is quite rare for the typical player in my games to intend to misbehave. All sorts of irregular stuff happens, but no one is planning on gaining an edge. They might not be paying attention and act out of turn. They "call your bet and raise you". They make sloppy bet/raises without saying what they intended. And yes, they pick up a handful of chips and only deposit a couple to call or bet/raise.
Most of the times, the "rules" end up favoring the angle shooters at the expense of the novices and weak players. That is bad for the game. It also isn't right. So most of the "rule" violations in my game end up with a warning and an explanation for why things should be done "properly". Eventually we get the regulars to know proper betting methods. Almost no one calls then raises anymore and we would actually call that a disallowed string bet for a regular, but not for a new-to-the-game visitor.
In a casino game, you need a harsh set of rules to deal with angle shooting and trickery. The casino doesn't care if the stupid tourist gets screwed - lots more suckers where that one came from. The betting rules do not have to be so harsh in a home game. Sure, we want a fair and proper game. And we don't want angle shooting. Let the host ask questions about unclear bets. Give the newer players lessons in proper procedures. Basically let players bet what they want.
One set in stone rule - - what you say is binding and takes preference over what you physically do. Even there we have questions arise when players use one of the "magic words" not intending to act. ( for example, "let me check for a spade" means they want to look in their hand before deciding what to do)
Bottom line, do what is best for the game which generally means catering to new players and weak players -=- DrStrange