There is 2 sides of the rebuys, unfortunately, I experience both. First, in my opinion, it is worthy, if you can handle it correctly, that's my real problem with the rebuys, it can put me on tilt and make more than I should. Generally, I always say, 1 rebuy, in few specific tourneys 2, but I can't keep it like this always, on the other side, even if I just look at the last month, 70-80% of my top 3 finishes come with rebuys. Especially, there are 20-25 tourneys per a day, what ideally I would play, or I can choose from those, that means max 15 tourney per a session, that is not so much, so the rebuys are reasonable for a while, depends on blind level. I try to avoid the rebuys, if the starting blinds under 20 BB, except 3-4 tourneys, where the structure is still good for it, mostly hyper and turbo tourneys.
After all, for me it is really worthy, if I do not go on tilt - how I see plenty players, making 5-10 or more rebuys, what can return only with FT, generally they relegate fast. I am okay with 1-2 rebuys. That's still profitable in long run.