Peak season is the same as any other day. You come in, load cars, take a short break regardless if you are working for 3.5 hours or 8 hours, work the second half and go home. There's more boxes and more routes, so more people. Lots of new people are hired, very few stay afterwards. Some people will walk off the belt and quit, some will wait until break and never come back.. If you're loading 3 cars and 900 pieces right now, chances are it's going to maybe increase 100 pieces or so. The belt speeds don't change and you wait on work some days. Most days you don't get off until after start time because trailers are late, planes are late, or whatever the other reasons may be.
Bonus points if you know how to drive a package car as you get taken off of preload and get the chance to drive for a few days to 12 weeks if you're one of the lucky ones. Otherwise, you work preload and go home, or work preload and go out on a route as a helper or on a golf cart...