Sometimes at my casino, I will throw in twenty minutes of cover play at a negative expectation game, such as a CSM dealt blackjack (although after comps the house edge is arguably reduced to virtually nil), baccarat or even roulette. What is the proportion of your EV you are prepared to sacrifice for the purposes of preserving your viability at a venue?

My personal opinion is, 10-15%, including tips, is a reasonable percentage. After all the house probably will return that amount from the house edge to the basic strategy player.