I get the point about mastering a skill. I don't try to master anything anymore just based on my available time. As a full-time computer/data scientist by day, and property owner by night, I want to be more competent for basic fab and repairs. I took an 8-hour "jumpstart" at a local arc and flame center for stick. If there are ever any open seats, I'd take the week-long night course to force myself to spend time in a booth with no outside distractions. My learning at the moment comes from small projects and needed repairs so I don't get that much time to actually practice the welding part. I try to do each thing a little better each time. I'll keep on digging around.