Here's their full schedule:
http://regiment.org/calendar/
And yes, top-level drum corps practice a ton compared to what most people think with regards to a HS or college marching band. It's a whole different level. When I was marching, our training camp schedules were pretty much the same as what PR is doing. Visual rehearsal on the field (working on drill sets, movement, etc.) in the morning, brass sectionals (working on music by itself) in the afternoon, full corps rehearsal (putting it all together, music+movement) in the evening. Outside of lunch and dinner breaks, you're rehearsing pretty much from 9 AM to 10 PM...every day...for weeks. Show days are a lot less demanding though...you generally go from 8 or 9 AM to around 3 PM, then you break to pack up and get ready to head to the show.
I know that our cook truck would put together meals based on an estimate of 4-5k calories per day, and still, anyone who had any fat on them, it'd be gone by mid-summer.