I'd agree it's really best for simple AABA structures and variations there upon:
http://www.songstuff.com/song-writin...aba-song-form/
As you've seen, you need to work with the interval. (I'll labour the point...)
Work out your phrase length. You phrase length doesn't need to be an entire verse of a song but it does need to have mostly the same chords on each repeat. So most blues is 12 bars of 4 quarter note beats per phrase and a lot of rock is 8 bars of 4. Some modern pop can be done in 4 bars of 4 but that really does mean a simple set of chords.
Once you know your phrase length,
tell the server. Otherwise, it'll be set to whatever the last people were using. I think the default is 16. I find it hard to live with under 32.
And the server thinks in beats, not bars (as it doesn't know the time signature). Obviously, 12 bar of 4 is 48 beats. You can happily jam blues with that interval for hours. "!vote bpi 48" if you want blues.
The other thing to remember is not everyone starts hearing the same remote client at the same time. If A, B and C are in a jam, A might hear B playing "at the same time as" C, even if B was hearing the same audio from C "the interval before", due to differing latency correction. This is unlikely except in extreme cases (very low transfer rates, short intervals). Just something to keep in mind.
Even jazz standards can be "AABA" in structure, essentially. However, you're looking for much longer sections, and a very long bridge. That rather pushes synchronisation with the backing band. I can be done with care. If each soloist waits for the backing band to start comping for one interval before they go off and then, after the solo, the comp carries on for an interval, you can keep things stable just about.
Halving the BPM is another way to double the BPI, of course, which may also help you get a longer interval. (Or even quarter the BPM if it'll go that low.) "!vote bpm 55" would get you "two for the price of one" on a 110 BPM interval.