no, since characters get better with more copies, 6 copies being the max.
Sometimes C1 makes a character quite a bit better, other times you'd have to go all the way to C6.
So if you like using billy or corin, or if you just want qingyi, then it might be a good idea to summon on it; it basically comes down to how much you like the banner units.
These two banners for instance were a bit annoying for me for example, since I do like qingyi, more than jane, but I have no interest in pulling more copies of billy, while the next banner has jane, but who I really want is seth and with a high as possible C# as possible; so if the banner was qingyi + seth it would've been perfect for me.