I go back and forth on this. I think that a cleaning step after compounding is probably a good choice to make sure that the defects are actually removed. I think the most recent reco was to use a 10% IPA to remove residual polish without softening the paint.
Per some posts, IPA can marr the paint surface and Mineral Spirits might be less damaging. Mike P seems to prefer MS. I don't normally have issues with IPA but personally had issues with a black Porsche and IPA. I have IPA, MS and prewax cleaners.
If you use a prewax paint cleaner like the Pinnacle Paint Lotion, you shouldn't need IPA after polishing. I got an email from the guys at Ultima who said that I could use UWW+ as the last cleaning step before UPGP to remove residual polish in place of IPA.
If it helps, I often used a Prewax cleaner before a glaze and carnauba wax on my '99, "00, '03, '06 and "08 BMWs and never used IPA until recently. It is probably the saftest way to get the job done before waxing.
Some of the sealants out there seem to prefer a clean paint surface so IPA might be appropriate in those cases. I didn't need an IPA wipedown before WG DPGS, Fuzion or OCW after WG FG3.0, OPT Hyper Spray Polish, Opt Finish, Megs 205, CG ProPolish (dusts too much for me), and a few others. I normally use IPA after the compounding step if necessary.
I hope this helps.