Do you do free art because you want to do free art and are feeling generous, or do you do free art because you basically want free advertisement for your art? You can solve both by having people who actually genuinely appreciate free art. People who actually do appreciate free art are much more likely to promote your art at least once and put their art on their gallery, giving you passive promotion. Free art can be beneficial for both, if the reciever actually put that shit on their gallery and/or promote the artist. I try to post all art I recieve, commissioned and free alike, in my gallery. I am not an ad company and I won't go out of my way to promote you, but I will show off the cool art I have gotten to friends and groups I am part of. Maybe even family, depending what art it is.