A couple other things I forgot to mention earlier:
1. Vegas follows offshore, offshore doesn't follow Vegas. Every Vegas casino is using Don Best behind the counter and checking the offshore lines. If you go up to the counter and want to bet on an obscure game like UC-Irvine against Pepperdine and you want to bet 4 figures, they're calling over the manager, triple checking Don Best to make sure they're not offering a stale line, and probably limiting you to $500 or so. You don't have to worry about this with the major sports, especially the day of the game, but those are the most efficient markets and harder to win at.
2. Some casinos move on air and will adjust their lines simply because they're staring at the Don Best screen and see the lines starting to move at other casinos. They're thinking "oh crap, we're about to get hit with a serious bet on this, better alter our lines". Certain casinos will not move their lines on air: if the line moves, they took a sizable bet or a bet from a "respect" account they've profiled. Naturally, if you know what casinos don't move on air, those are the ones to pay attention to. I couldn't care less about Bovada, sportsbook.ag, or those mickey mouse casinos like Bet Islands, Bet Revolution, etc. Chasing steam because you're following a line that moved on air is completely meaningless. The point is to tail the sharps and you're tailing nothing but casino fear.