I have a limit that I will not exceed. That magic number for me is 10. If I go above ten, well I need to sell someone, not because I have to, but because 10 is what i am comfortable with. I am at 8 right now (including 2 babies from this year). I have not bred any back yet for next year, I would sooner wait and place my babies, and if I don't place them right away, so be it, I am still below my self induced "allowance". If I don't breed any back before fall, then so be it, it is my love and my hobby, not something I must do.
As others have put it, it is too many when they don't get what they need, the attention, the hoof care, and floatings, the vaccinations, when you feel that you are stretched so thin that you are ready to snap. When your family is placed second and your horses are your first priority.
I must also add that the horses I have are ones that I have strived to get. I have an attatchment to them, but I also have a considerable amount that went into them monetarily. With that said, I personally feel that I must be able to maintain the upkeep on what I have already put money into, rather than continually look for more.
Carolyn