Many times artists copy the work of other artists they admire as an exercise, sort of like doing pushups or going to the driving range and hitting wedges for 2 hours. The main benefit that comes from painting someone else's work for fun and practice is you usually end up with a pretty nice little painting. Now I have done this and even sold them to other people but only after I attribute the original artist and make it clear that I have created a rendition of another's work. I have always admired Edgar Payne and I painted one of his paintings for practice. Golly, it was almost like having a lesson from Mr. Payne. Thanks very much, pro!