It depends.

With a set and no flush/straight showing, pretty much always willing. Below that, depends on cards, table, reads, etc.

I've gone all-in with TPTK (AKo with Kxx flop) and I've also folded AA and check/called small bets to the river with trip Aces (smelled a slowplay on a flopped straight from a guy that loved to play low suited connectors).

- Jeffrey