Ctrl-S starts an I-search, instead of /. You then start typing what you want to search for. The results immediately appear; you don’t have to press enter. This will search across the docs for an entire project—with man, you may have to dig around with apropos first to find what you are looking for.
You can then hit Ctrl-S again to go to the next search occurrence, hit enter to stay where you are and exit the search, or Ctrl-G to exit the search and go back to where you started.