A lot of CASINOS use what is called dual points. All the points you earn for playing the machines and cash in; say 4000 points equal $10.00 have a duplicate amount of money used for comps. The cashing in or not cashing in of your points has no bearing on your food and room comps. Even if you do not earn enough to get your room comped, usually you can get the CASINO rate which is $35.00 or some greatly reduced price.
It takes a lot of $15.00 play to earn comps through table games but buttering up the pit boss will usually get you a free meal with out much effort.