Yep. One session a day, 20 or 30 minutes per session, is a good maximum. You can meditate yourself into a dissociative state, with florid hallucinations, delusions of reference, and other psychotic symptoms, if you overdo it; that's a relatively common event at those meditation marathons that some Asian traditions unwisely offer to American students. Discursive meditation doesn't do this anything like as often as some other methods, but instances have been known when somebody spends many hours a day at it with inadequate preparation.
Monks can meditate all day, but that's because they eat a very carefully chosen diet and stay in the sheltered context of a monastery. It's also quite common for novice monks to wig out and be guided back to sanity by experienced elders. If you're not in a monastery and don't have an experienced elder on call 24/7, don't go there.
If you have a couple of months of relatively free time, plan on upping your ritual work a little -- say, doing a more complex ritual working once a day -- and learning a new method of divination. Then spend the rest of your free time doing something creative and fun!
Re: Are there any warnings to be aware of?
Monks can meditate all day, but that's because they eat a very carefully chosen diet and stay in the sheltered context of a monastery. It's also quite common for novice monks to wig out and be guided back to sanity by experienced elders. If you're not in a monastery and don't have an experienced elder on call 24/7, don't go there.
If you have a couple of months of relatively free time, plan on upping your ritual work a little -- say, doing a more complex ritual working once a day -- and learning a new method of divination. Then spend the rest of your free time doing something creative and fun!