I think the current session timeout is set to something like 10 minutes. I would like to request that it be lengthened to more like 20. The reason is that sometimes, it takes time to write up a proper response with the proper links/etc for articles, and then users are timed out while composing their reply. Or, like me, they may be looking at the site while taking a break from work. Distractions happen (phone calls,etc) and so it requires logging in repeatedly with the short timeout length.

One workaround is to use the “go advanced” button while composing. Every time you need to take a break or step away you can hit “preview post” and it will essentially save your progress. You also have to make sure that when you log in initially that you select the option that keeps you logged in.

I stay logged in basically forever, and I believe I check a box next to the login that says "remember me" or something like that, like Urbanized said. I literally can't remember what it's called because it's been months since I logged in. Also, for me, it's a bit hidden since I block some scripts/ads/etc., but it's there and it works.

There's also a "Restore auto-saved data" button at the bottom of every text box that you can maybe use to get a post back, not sure how often it auto-saves, though.

I haven't been logged out in months either. Once in a while my phone decides to log me out of pretty much everything but that's a couple times per year.