I always check and, to date, none have been missing. I also keep my shoes on for takeoff and make sure they are back on for landing. It's not just the protection against fire, but I wouldn't want to be running barefoot across the tarmac at LAS / PHX / DXB / RUH etc. in the middle of summer.

I do also check where the nearest exit is, and I always keep my keys, phone, wallet and passport on my person.

It really is a source of frustration to me when people don't follow the safety briefing and / or don't do the basics like fastening seatbelts. I was recently flying with AA and there was a couple in the adjacent row who didn't fasten their seatbelts. I pointed this out twice to the crew who did nothing. When I was disembarking I spoke to the captain who was seriously annoyed at the fact that his crew hadn't enforced the rules, specifically after they'd been made aware of it.