I barely look at any of them unless I'm buying clothes or shelling out a lot of money - the former has only happened once, and the latter...well, probably never will xD
We do stress over it, but to be honest I think we're right to. Every now and then I do look at shop policies, and in total I've done it about four or five times, and literally NONE of them had filled them in. I reconsidered what I was purchasing but decided to go ahead anyway and there were no problems, but it can be a pain. If people take a long time to deliver an item I look at they never seem to have it filled in.
Shop announcements I check for shipping times, alternative sites (personal websites, blogs and such just in case I might miss out on an attractive discount) and maybe custom item info.
About page...I have never looked.
Despite never really looking at any of them, I DO fill them all in. If someone wants it, at least it's there. The problem is remembering to update things if something substantial changes like refund policies or something.