There are at least 3 different situations here:
1) Regular MTTs, that offer the option to reenter, if you lose all your chips
2) As 1) except there are bounties (PKO, KO)
3) R+A tournaments, where you can rebuy (add chips), if you drop below the starting stack and add-on, when the rebuy period has ended
For 1) and 2) the answer is, that you should reenter, if you would also have played the tournament, if you were to select a tournament right now and did not play it already. There is no difference between playing the same tournament twice and playing two different tournaments. For situation 2) you generally want to register as early as possible, because when bounties have been collected, there is less money to play for, so you are getting a "negative overlay" by entering late.
So if your general policy is to late register until an effective stack of say 30BB or 40BB, then you should also reenter, unless you prefer to play another tournament or want to reduce you table count. For KO and PKO events you should generally only reenter, if you bust very early, like you ran KK into AA or got oversetted or similar coolers. Mystery bounty MTTs fall under 1), since the bounties are not in play, while late registration and reenter is open.
For 3) the answer is, that you want to make it to the add-on break, since the add-on chips are sold at a discount, so you should normally rebuy as many times, as is needed to achieve that goal, but no more than this. Of course if you are on tilt and just had enough, its better to give up and forget about that particular tournament rather than rebuy for the 4. or 5. time, if you keep getting stacked. Since you are planning to fire more than the initial buyin at a R+A, the normal bankroll management rules do not apply. A $1.1 R+A can be compared to a $3.3 regular MTT and require the same bankroll.
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