Can playing the same game for long, extended time periods damage the physical media for the games in any way? I've been playing the same game (GTA V) for 5 hours now. I love this game and don't want to lose it, so I'd like to know if I should let it rest for a bit.
Playing the game for extended periods of time shouldn't wear the game out any more than playing it a lot over a long period of time so long as your xbox is level. Basically the DVD is just spinning when data is being loaded and otherwise is sitting in the tray, which is what the disc is made for. Just keep an eye out for the fan doing 'too much work' or continual loud spinning of the disc. Basically, unless you hear odd noises or the xbox drastically changes its behavior, you should be fine. And if you hear odd noises, that probably means whatever could get broken already has been, and it's not from strain but just normal use. *Also, make sure your vent ports are clear and your not playing in a room filled with dust. :)
PS. If you're really concerned, you can copy your disc's data onto the hard drive (install the disc). That way load times are improved and your xbox doesn't need to read much data from the disc (only makes sure the disc is in so you can play the game).