Seeking Advice On Cover Play

Is cover play worth the effort? I have played for years using minimal cover totaling about 500 hours of play, and I've been backed off from about a dozen casinos. I've been backed off in as little as 20 minutes of play, and I've played at some places for 20 hours with still no sign of heat. I usually play 2 hands of 10-100 or 25-200 for a 6 deck shoe. So for those with more experience than me, how much would I be able to increase my playing time at a particular casino with your favorite cover plays? Or is it as I suspect that some casinos concern themselves greatly with catching card counters and other just let it slide?

Being backed off about a dozen times in 500 hours of play and at your bet level appears to me to be way too many backoffs and that there is something else going on.
Perhaps one backoff earned you a backoff in all sister properties of a company like MGM or HET?
Perhaps you are very obvious to pits and the eye?
Perhaps your persona at the table shouts counter?
Perhaps many of the places you play are real sweatshops that backoff tons of players?

As you can see, a lot more information would be needed for me to give you any kind of educated guess here. I do know that many of us play at higher levels with bigger spreads and get far fewer backoffs without giving up any or much EV with cover plays.

We do need a lot more information I agree with hate that is a lot of backoffs for that amount of time played. The culprit may be the way you spread. When I have been backed off, it mostly it has been my fault: playing too long at a table/casino, sitting out negative hands while staying at a table. I was welcome at the Showboat in AC for many years, had one good shoe (between $2-3k at a $25 table) and got half-shoed on the next shoe.