is the limit/recommendation to number of subnets associated to AD site

is the limit/recommendation to number of subnets associated to AD site?

I have a requirement and wanted to check on the scale ability for subnets in AD sites, i have a recent requirement to add 500 subnet to a site, though not encouraging we have to add them. We wont be able to add a subnet mask, so this has to be added.

Looking for thoughts/recommendations. 

Thank you Vijay