I saw the current Outsiders tour - and curious (no judgement, just curiosity,) based on this particular cast and other recent Broadway and tour casts I've seen...
25% of the cast had 3-name stage names - even when it is almost a certainly (like "Norbert Leo Butz") that it was not necessary for Equity during duplication reasons (like "Philip Seymour Hoffman"). Other casts recently have had similar %s with lots of actors using 3 names even when it seems clear they would not be mistaken for others in Equity.
It would be interesting to know from insiders... Are college acting/musical theater programs, agents, or others recommending 3 names are better than 2? It seems far more prevalent than decades ago, when a review of Playbills show few actors not using just two names.