Discovering the secret of your swing

I went to the range last night and managed to get a bay with a mirror for once. Just loosening up and realised that at the top of my back-swing the club-head was aiming about 15 degrees left of the target line. Possibly explains why I have been blocking so many shots left all summer.

So I adjusted my swing accordingly which as a consequence led to my right shoulder staying closer to my body and then proceeded to hit glorious shot after glorious shot.

Now Im under no illusions that this will translate onto the golf course in any way, we have all been there before. But it sure feels good at the time.

But my question is has anyone ever had this kind of eureka moment which has actually been exactly that and led to a massive improvement in their game, or maybe just led them to understanding their swing better?

Personally I think the main reason I was hitting it so well is because I'm off to Scotland on a four day golf trip tomorrow and felt totally loose and relaxed. Which would lead to my second question, how can you take your range head (and what I feel I've learned) to the course, I'm not great at doing that - always way too tense for the first few holes.