I think it depends very much on the situation.
In some environments - especially around the fire - seats are very communal...X number of people, X number of chairs, and people come and go throughout the weekend. Chairs get moved around to accommodate number of people, temperature, sun, smoke, etc. and none really belong to any individuals except people tend to sit in their own if it's available. In these circumstances, if you (all 'you's general) leave your chair to get a drink or use the facilities, then it's still yours when you come back. If you go take a nap or a hike, you select from the available seats when you get back. If you want your furniture to be available when you return, remove it from the common area when you leave, then place it in the best available location when you return. You don't get to reserve a location by leaving your property there, or make people remember it's yours and leave it empty or move it out of the way when trying to sit near each other to talk or sit the best distance from the fire. In short, don't leave it in the common area if it's not for common use.
Part of etiquette is understanding norms and accommodating them as much as is practical, so I believe your answer really depends on the group.