I'm not sure how much you can do about this, since the documentation is automatically generated and the Time module is complicated (as documented here).

That being said, the Core_time_float documentation is very cluttered, which makes it difficult to tell which hyperlinked module is the actual module that is exposed by Core.

For example, there are 3 top-level modules called Span. Two of these link to the empty module. One of them links to the exposed Span module.

I'm personally pretty comfortable with OCaml, but even I had a hard time navigating this documentation. I would imagine that a beginner would have even more trouble making sense of this.

I think this should be a priority for any new documentation efforts, since it is a fundamental module when using other libraries (such as Async, which is why I was looking into Span). Even just adding some prose to help people navigate to the correct modules would be great.

I'm playing with Async in my free time, and if I make enough progress I'll be happy to submit a PR with some Time documentation.