But my point is they really need to limit the # of KSS they're putting in MM. Personally, I think they should be limiting the number of girls they add to the KSS in general.
Over saturation is a problem HP is going to really feel (if they haven't already [Tsubaki]) very soon if they keep this sort of thing up. Over saturation in all areas+no freshness with amateurs added in.
With regards to over-saturation, it wouldn't be a problem if each group had a unique identity/sound. Back in the day, H!P could roll with MM, MKB, Tanpopo, Mini Moni, Pucchi Moni, CM and a slew of shuffle units (and later with BK, C-ute, GAM, W, v-u-den, H&A) because all of those groups sounded distinctly different (despite sharing members). It wasn't over-saturation because each group had their own look, their own sound and their own personality. Is there really that much difference between MM, ANGERME, KF and TF? Is J=J all that different from any of those groups? There might be differences on the margins, but they're pretty minor compared to the 2000s H!P lineups.
H!P can sustain more groups, but only if they do more to differentiate between them. I don't think they have that in them, though, as they seem to have become quite risk-averse wrt their girl-group formula.