Focus your efforts on creating material that will be useful to players.
Too many settings blather on and on about stuff that happened ten thousand years ago, or explain the vagaries of the weird calendar systems that the nine different cultures use. In general, players never use this stuff.
While you want your setting to have enough of a backstory, enough history, to "hook" the players, you don't want to put them to sleep. At the very least, do not emulate boring history books when you write your world's history.
Anything that you can sum up in bullet points should be five or ten bullets.
Here's what players really want to know:
- What is this? What makes this campaign setting different than all the other ones?
- Who am I? How do they create characters that fit into (and hook into) the setting?
- What's happening? What is the immediate situation their characters face?
Anything you create beyond that is likely background they will gloss over, even ignore, until it's relevant to their characters in play. In other words, you didn't have to write out ten pages for them to read; it could have been a one-paragraph Arcana check at DC 18.