Rebuys are strange beasts. There are elements of both ring and of tourney in the first hour. The first hour is the rebuy period, and depending on the table you are at, it can be very sane to totally insane. Not being flip, just sharing experience.
I would suggest you try these out at a buy-in much below what you would normally buyin to a regular MTT.
I start feeling uncomfortable at 5 original buy-ins. There will be an add-on at the first break, so that would make 6 buy-ins. Using a $3+.30 rebuy as an example, that means I'm willing to invest $18 +.30 into this game. I never like to get even close to that. With a much smaller field and a better chance for the money a $20 MTT might be a better game. Fewer risk takers. But they won't have the prize pools the rebuys have.
Try the first ones using this motto; " I am going for the moral victory of not rebuying at all".
They can eat your bankroll up much faster than you thought possible.
During the first hour it is not uncommon to see one or two players rebuying many times (10 rebuys is not so odd). I've watched where these loose players will get lucky at the end of the first hour, win a big pot, and maybe get all the chips they have bought. From their POV they may have had faith that would happen, and were investing in a big stack in order to hit the first break with the big stack. Play during that first hour is generally loose at table with those types in the game.
After the first hour, play calms down. Not totally down though. The first hour tended to get the juices flowing for action junkies and it might take 20-40 more minutes before they return to sanity.
By the second break play would be considered normal, and in many you may be close to the money. Rebuys are often turbo, or accelerated and the game moves fast. In any accelerated tourney the play will be, of necessity, looser than a normal tourney.
The period when the bubble is approaching tend to slow down a lot. Two reasons;
1. shortstacks go into a delay mode thinking that if they can slow things down other tables will lose players and these shortstacks can sneak into the money.
2 Big stacks figure they can slow things down and coast into the money, while wasting blind time. This results with the shortstacks losing time while delaying and getting fewer hands per blind level.
These are different beasts than regular MTT's. They can be exciting as hell, with dreams of big payouts. They can also eat you alive.