I'd just point out that theoretically not all skills can be perfected in practice, even if the steps comprising them are perfectly understood.

For example, an expert practitioner of golf - or billiards, etc - may exhaustively understand the physics and postural adjustments needed to hit a hole-in-one. Depending on their skill, they may be able to accomplish that goal quite often. Yet it would be unrealistic to expect them to do so every time. This very impossibility is what makes it into a sport, rather than an exercise in engineering.

This example suggests that, though a perfect method (hitting the ball exactly-so) may theoretically exist, one's own fallibility makes that perfection unattainable. An analogy between this and non-disruptively observing and entering hypnagoguic imagery could be made.

On the other hand, some skills can be effectively mastered. The simpler operations of blacksmithing can be done a thousand times without any error save that caused by fluke.