Some books will cut you off when you're a proven winner.
Some books will never cut you off.
Some books will only cut you off if you abuse their bonuses.
In Vegas, its tough to get a lot of action down period. You'll have trouble putting 10k on a line in Vegas unless you're strongly known to the casino and generally only then if you're a loser / whale elsewhere in the casino.
As for someone who worked for a book, check the YouTalkFunny thread in The Well:
http://forumserver.twoplustwo.com/showfl...=0#Post12933167
There's also quite a bit of discussion about cut off limits and practices at various books in that tread.