It's a truly exhausting strategy. It takes so much work and for very little payoff. And often (usually?) it just makes everyone involved mad at each other and burned out, even worse off than before.

There are ways to make "foment a split" work if your goal is to enrich a particular group and then peel them off of a dead-end org to instead do good work. To me this only makes sense if that group basically already exists but is stuck being useless.

Some commie factions in DSA are basically doing this, knowingly or not, and with unclear success. All DSA factions are basically premised on exhausting their opposing factions as much as possible by being a (often fairly insufferable) advocate for their positions. Obviously the libs are the most guilty of this, they tolerate genocide and tokenize etc etc, but this sets the battleground up: keep opposing these libs within that group and tiring them out or go to another org where you don't have to deal with them, at least internally. If you do the former, you are a hair's breadtg from an entryist + split position, as you are not going to convince the libs, generally speaking, but you may eventually get them to force a split on some key issue, and when your faction is large enough to either take over the org or leave and form a new one.

Entryism is basically this same thing only less authentic because you don't even think of yourselves as truly part of the org, and instead try to join and take over as fundamentally external.