There is a lot of variation in riding.
It actually does work fine if the lead person is on drops or aero bars.
If you have a mix of stronger and weaker riders, it may be advantageous to not rotate. If you're pulling somebody slower than you, you may be able to ride on flats instead of the hoods.
For reasons I have yet to fathom, the group that is going 20 mph and I'm hanging on with my tongue hanging out, if I get to the front, then 14 mph will be too fast and I'll be dropping people off the back.
A lot of the pacelining that I see on club rides is an "every man for himself" style that does not involve trying to keep a group together. Actually pulling slower people without dropping them is its own skill.
The dynamics of a tandem are different, and it's hard to draft a single bike with a tandem. So the general rule is that the tandems draft each other, or always pull, or just ride off by themselves.
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