Google has flat announced that they don’t care about multiple H1s. If the content is arranged in an intelligent and coherent way, it won’t make a difference. Use the headings hierarchically to break up main points and sub points, and you’re golden.
Heck, you don’t even need an H1. You can get away with an H2/3/4 as the topmost heading on a page, and if you follow the hierarchy from there you’ll be just fine
There’s no limit — neither upper nor lower bound. H1 elements are a great way to give more structure to a page so that users and search engines can understand which parts of a page are kind of under different headings, so I would use them in the proper way on a page.