The greatest temptation of defenders against a shooter is to stuff the shooter, or even better the crowd-pleasing swat into the stands. It is also one of the most common and easiest fouls to call.
Today defenders – and especially the Bigs – should be taught to stay within their vertical space (shoulder-width to the ceiling), including their arms. I cannot count how many times I see a defender go straight up, then succumb at the last second and swing their arms trying for the big block, not realizing that just being up there has a good chance of affecting the shot (making them miss).
Emphasis is put on not penalizing good defense: If I see a player jumping straight up with arms straight up, I am unlikely to call a foul (There are exceptions e.g. shooter already in the air).
What happens often at lower girls levels is what I call the birds nest because the ball reminds me of food being fed to baby birds in a nest: A1 shooting the ball, B1, B2, B3 trying to block, often repeating this several times. If B1/B2/B3 are going straight up with arms in their verticality, play on.