Every doctor I have had has recommend taking breaks if and when possible. I try to do it myself, and I think it makes a difference. The research on tolerance to medications is not well agreed upon. I am not expert, but I do not see any biological way that the human body would not gain a tolerance to some degree when constantly exposed to an exogenous substance that alters dopamine, GABA, etc..

Nicotine tolerance is real. So is caffeine, cocaine, meth, etc.. I do not see how our medications would be any different.