Pretty much every game, thanks mainly to beasties with Improved Grab. Thus, I know the grapple rules fairly well.
The players have developed a great counter-tactic for fighting extra-sized beasts of grabbiness -- the cleric has a ring of freedom of movement, and the sorcerer knows benign transposition (and has a ring of wizardry, and thus can cast 13 or 14 first level spells per day). So if someone gets grabbed by the gigantic critter of the week & is in great danger, the sorcerer switches the victim with the cleric, and the cleric wanders away. One fight, they did that dance three or four times (there were a couple of Improved Grab critters).
I'm waiting for the time they get really cunning, and the cleric casts harm, and holds the charge. Ouch.