For each piece of work, yes. For infinitely digitally copied art... does a carpenter get 5 cents from each person who sits in a chair? Does the key grip get a percentage of a cent each time the VHS is resold? Musicians should get paid per performance, painters per painting, etc. Any agreement with publishers is extra, imho. Art is a miracle, but if you can't keep up performances, or constantly create something new, you should have practical skills to live off of as well.