We all have different limits based on significant other (for some), space time and most importantly ability to care for all the animals properly without loosing passion of feeling like it's a burden.
As someone who breed my limit is around 60/65 animals in my collection (not counting those that are produced during breeding season) when I retire from breeding in 10 to 15 years I will have something like 10 snakes and 2 geckos.