I wish they checked more often.

One flight I had this guy try to self upgrade and flight attendant notice him immediately. He then tried to ask if he could sit there. FA told him he could if he paid the upgrade fee. He said he would and then when FA came back, he didn't want to pay and said "can I just sit here for takeoff?". FA told him no and told him to go to his assigned seat.

I see more likely to get an empty middle next to me in exit row. Row 1-3 often get filled for whatever reason. I've seen them out a lap baby in row 3, theyve had disabled people there and I think when plane gets full, they fill the exit rows last.

That being said, I posted a year ago about this overzealous FA out of Jamaica. I was in the window seat and this guy was ticketed in the aisle. He tried to move over to the aisle exit row in the otherside bc no one was in that row and this surly FA told him to go back to assigned seat. She was really nasty in the way she said it. I even made a comment to the guy when he was forced to move back.

I had never heard of someone not being allowed to move over like that.