Generally speaking, too much of anything is bad for you; moderation is the key. Having said that, I refuse to believe that ten to twelve hours of sleep on Saturdays compared to seven or eight hours of sleep Sunday through Friday is going to present a problem. Furthermore, how much of said ten to twelve hours are you actually sleeping? It takes me at least an hour or more before I actually begin the process, not to mention getting up to use the restroom, etc.

In the end, if you are worried that you are using lucid dreaming to escape reality, chances are you aren't.