The more, the better — as long as the writing is good. But usually, sticking to 5 or fewer LIs gives the author better control, and each character stands out more.
depends a bit on the length of the game tbh. like heart no kuni no alice has a lot of them but i think the time each li got was enough. i am fine with short but good stories too, if that is the route the game wants to take fine by me. more characters take more resources though... so after like 7 i might start questioning the quality of the game(eyeing paradigm paradox)
I feel like anything more than five and maybe six would be too much lol. Would be concerned about the writing if there's a lot of LIs unless it's like a live service game where they can gradually add updates rather than all at once.
I guess when the developers can no longer make the characters stand out against each other and have character development that is when you know it's too many LIs lol. Like Paradigm Paradox it was long and TORTUROUS. some routes felt underdeveloped and i couldn't even feel for them anymore and i just want the pain to end. But if they can work it then be my guess but i dont want half developed slap sticks.