I think having too many groups in a company might delude their success.
Case in point: JYP.
Twice is super-famous and still has lots of fans. I don't think they are the issue in what I am writing below this.
But they also have Itzy, which is basically their 4th gen group. Only, they then also have NMIXX.
Neither is doing amazingly. Itzy had a great debut and hype, but since there is already a newer group in JYP it makes them look more like past glory. I had hoped for them to stay JYP's new focus for a bit longer.
I feel the same if SM would debut another girl group while AESPA still is 'the new girl group' in JYP.
I don't definitely think I am right with this, but it's just a thought I have and I wonder what you guys think.