Yes, it can be work. If I am getting ready to take a shooting class I go out with the intention of brushing up my skills. No plinking or screwing around. All business. By the time the class comes around I am looking at it like work.
Often when I go out to shoot I spend a certain amount of time trying to seriously better my technique and then finish up with some informal plinking. I did it today. I hung up a couple 25 yard pistol targets and shot groups on paper. I tried to shoot with perfect technique. After a few targets like that I fool around shooting junk lying on the ground. I actually think they both provide a good learning experience, but the targets are much more stressful. I still think it is fun or I wouldn't do it, but the intense concentration and self-evaluation gets to you after awhile and it is time to unwind.
I shoot 90% of the time by myself, by choice. I am usually trying to accomplish something and don't want any distractions. I don't have any friends that want to seriously train. The guy I shoot with fairly often always shows up with the wrong gun even after we agree to train. I might say, let's due some close in work with carbines-he shows up with a scoped rifle..... He also can't just take turns shooting a drill. When it is my turn to shoot, he starts shooting at something else at the same time. So, the only time I call him is if I am just going out to plink.
I also hate cleaning guns. I never shoot more than two guns in a session. My SOP is to take out two guns and shoot them until I am tired of them or until I have a burning desire to shoot something else. I then clean them and return them to the safe and start over with two more.