A few years ago I did a 10 Minute challenge for class. As many times as I've painted an apple, I still learned & improved with each painting. Becoming familiar with my subject allowed color temperature, edge quality & brushwork to improve. Confidence in the understanding of the subject builds stronger paintings. Set a timer, chose a subject, paint at least 6 versions and focus for 10 minutes on each one. You'll be surprised a what you learn.