Hi Brian and Matt! If you look at some of Glen Vilppu’s drawings, he is in his 80s right now, probably approaching the 90s, he still draws actively and he seems to be doing good even still. When he was in his 70s, that’s when some of the DVDs (Free to view on Youtube if you search for ’em) were filmed and he draws so smoothly! His hands just seem to glide over the newsprint. He is an expert on anatomy and taught it at multiple leading animation companies, like Disney. His method of teaching relies heavily on simplifying form into box and spheres.
In my opinion, it must probably be the thinking style that evolves or changes with age rather than the mark-making deteriorating. I always think to myself, “I would never let myself become sloppy with age” but in their defense, after half a lifetime of doing realism and careful drawing, I can totally understand that an artist would like to evolve and move past that.
I think Bouguereau lived pretty long too and his latter paintings also still had the chops!