Both, without a doubt for me. Every railroad I've built has had provision for continuous run. As others have stated, sometimes you just want to see a train running without having to "operate" it. But watching a train run around in circles, even large ones which twist all around, gets boring real quick if that's all there is. I've been fortunate to have a fair amount of space available for my layouts, the smallest was 5 x 14. On that one, only the run along the front 14' length was visable, both turnback curves and several staging tracks along the back were hidden. A turnout from that front track climbed a grade to the rest of the llayout, above and behind that lower main. Whenever I was in the basement, a train was running on that bottom loop, even if I was just going by for tools for some project I was doing elsewhere. But when I operated, I ran the rest of the layout. My currant layout is two levels, with the bottom being continuous run (but when "operated" it functions point to point) and the upper level point to loop. I had thought about posting my track diagrams in the trackplanning section along with my reasoning for doing things the way I did, but wasn't sure anyone would be interested. It would get rather long, like this post! If anyone would like to see it, let me know.
Gary