People will and do stake their claim to chairs early in the morning & don't show up until afternoon. On our last cruise chairs next to us had items on them when we arrived about 8:30 and NO ONE showed up until about 1:00 which I thought was just WRONG! There were others walking around looking for chairs together all morning. In my opinion, if a chair is unoccupied, i.e. NO sign of life, for an hour, you should tell someone w/ Carnival and leave it up to them whether to remove the items. I, personally, would never touch someone else's things............you never know what you could be accused of.
THen you have the other scenario which happened to my son. He had been in his chair all morning & left to go get lunch from the Lido buffet and when he came back someone was in his chair and had just thrown all his stuff to the side. He wasn't gone 15 min...........brought his food back to his chair to eat! So we need to reasonable about the amount of time a person is gone to consider it "saving" a chair. We all need to eat & go the bathroom. Or someone might be in the pool or in line for the slide.
Its such a shame people can't be considerate of each other. We're all there for vacation.......fun & relaxation. Just a little common courtesy would solve the problem!