I can quite honestly say I've never given it a second thought.
Yes it might be pleasing if my site appears at or near the top of a search, but I couldn't care less if it doesn't.
I did a few experiments when we switched to XenForo earlier this year, to see just how good the built in SEO is, and just by adding a single word to a Page title, it pushed us from page 8 to the top of page 1.
Other than that I have done nothing.
For the 3 years prior when I was using phpBB software, again I did nothing at all to do with SEO, and really wasn't bothered at all about it.
In fact, our most valuable content is hidden from guests, so it doesn't even appear in search engine listings.
My opinion is if there is content on your site which is useful to others, they will find it.
Mostly this will be from members posting links elsewhere, which others will then click on and likewise, if they find the content useful they will also pass it on.
I used to be the same about my AV/Home Cinema equipment; constantly tweaking, adjusting, testing, reading articles on how to improve it, tweaking again, retesting, etc.
Then it dawned on me that I wasn't actually using it for what it was intended.
Now I just use it and enjoy it.
(This is of course my personal opinion and not a reflection on XenForo or its built in SEO capability.)