More segmented Facebook audience seems to perform worse?

I have recently had a strange experience, and was wondering if anyone else has had something similar happen.

I was running a lookalike audience on Facebook, which I subsegmented into about 15 different ad sets. Each group targeted the overlap of the lookalike audience and one interest, except for one catchall "everyone else in the lookalike audience" ad set. I then carefully applied exclusions to take care of the overlaps. In other words: everyone in the lookalike audience was being…

More segmented Facebook audience seems to perform worse?