[davidross]

My thinking with JJ or TT is that I’ll raise if I can limit the field to 3 players or fewer, or If I’m on the button and there are 5 or more. With a big field you almost certainly have to flop a set to win, so your worst scenario is a raised pot with 4 or 5 people in. You don’t quite have the right odds to flop your set, and you are unlikely to win unimproved. You’d rather play that hand for 1 bet.