How many keywords should you focus on per page?

Got to know from ahrefs, lately. The keyword stuffing does not work or matter nowadays. It may still work for some but not all. If you have good content with even 1 keyword, you can rank. But on other side adding more keywords, may not help in ranking. Instead related keywords can help.
So, optional 3-4 keywords are good, for now(Until google stops giving marks to this)

If your blog length is worth 2000 word you can focus on 5-6 keywords