When players bust, the value of each chip goes up, because there are now less people, who can reach ITM. This is also known as ICM. So by entering late you do sort of get a "discount", because you have outlasted some opponents by simply not being there. You also save time, which might be important, if you are a tournament grinder. For tournaments, that start very deep like 150-200BB, usually not much happen during the first blind levels. So maybe its fine to miss out on those and come in, when a starting stack is 60-70BB or so. Especially if you are not so familiar with deep stacked play.
However in a PKO money will have been taken out of the price pool, because some players have already claimed bounties. And this tend to be more important than ICM, so in a PKO there is no reason to enter late other than maybe not having time to play, when the tournament begin, and/or spotting a tournament, that will have a significant overlay. Like the price pool is $1.000, and players have only contributed $750 two minutes before the end of late registration.
And even in normal MTTs there are clear disadvantages to registering late. If you are a winning player, you will have less time to find good spots, and if you enter very short like 10-15BB, your skill edge might not be enough to overcome the rake, even taking the higher ICM-value of chips into account. If you are mostly playing for fun, you get less entertainment for your buy-in investment, when you enter late and maybe only get to play a few hands, before you bust. If you think, moving all-in preflop with 10-15BB is great fun, then you can just play a Spin n Go or other hyperturbo SnG instead of a big MTT.
So to sum it up for PKOs the best strategy is to be there from the beginning or at least enter as early as possible. For regular tournaments its less clear, since there are both advantages and disadvantages of entering late. And of course this also apply, if you consider reentering to a tournament, which allow this. In a PKO you should pretty much never reenter, unless you run into some big cooler like set over set very early in the MTT. But in regular MTTs you can reenter, if you want to, maybe down to around 30BB or so. After that I would usually be done, unless there is likely to be an overlay.