I was recently watching the first film in the series 'Armchair Odeons', and a few of those interviewed used extensions; one saying that his could hold 6,000 feet; making the viewing of most features possible without a break. For myself; I am happy to change reels after 45-60 minutes. We had intermissions in the cinema, and changing the reel gives us something to do between watching the next part. You also have the opportunity, to make yourself a drink before continuing the show. I sit next to the projector so that i'm handy should anything go wrong, or picture of volume need to be adjusted. I would find sitting for 3 or more hours without a break rather too much. If my film has the original leaders and tails, then I try to preserve these, by adding extra leader and tail. For me, it's all part of the original film, and some contain interesting information. Ever since I got into the hobby, I have always enjoyed watching the countdown; something that you don't get on digital. I should miss all that if it was removed.