Pinterest doesn’t have a limit on how many pins your account can create or how many you can upload. In theory you can make 100 pins for a well performing blog post and you can make 1 pin for a poorly performing blog post. Of course the timeline would matter as well.
Just for an example, i have 2-3 posts that I make at least 10 new pins every month for because they are evergreen for my audience. And then there are about 20 other that I create only 1 each. Not to mention i would also add new pins for new blog posts.