The subject of working faster without working worse is one I've thought about a lot as a professional, because speed and quality are in genuine tension.

The first speed improvement: decisions made earlier. Every decision you defer to later in a piece costs more to make. Deciding on the light source in the thumbnail is free. Deciding on it after you've rendered three hours of carefully lit detail is expensive. Front-load your decisions.

The second speed improvement: establishing the rule and trusting it. Once I've decided this scene has warm golden late-afternoon light, every subsequent color decision is constrained by that rule. I stop re-evaluating and start executing.

The third speed improvement: separating the evaluation phase from the execution phase. When I'm painting I'm not evaluating the painting. When I've stopped painting to look at the painting, I'm not holding a stylus. These modes require different mental states and switching between them mid-stroke slows everything down.