Rhythm and tempo
Nice word, rhythm, with a slight suggestion of onomatopoeia. It's related to tempo, but different in a subtle way.
Tempo varies from individual to individual. Some golfers swing fast (Harrington, Hogan, McDowell) and some swing more slowly (Els, Bobby Jones, Jacquelin). At least it looks that way.
What all these great players do, however, is swing with rhythm. This is how they generate clubhead speed that the average player, no matter how strong, can only dream about.
Rhythm is closely associated with the kinetic sequence (the order in which body parts and the club move) during the swing. Finding a rhythm that optimises this sequence is the key to generating good clubhead speed, while maintaining one's posture and balance.
I've recently realised that rhythm is only thing (once you have your set up fundamentals in place) that it is worth focusing on during a golf swing. Other swing keys, and there are hundreds, do little to help with this sequencing - and often interfere with one's golf swing.
After all, you have time to set up, to create a good athletic posture, and you even have time to take the club back properly at the start of the backswing. But after that, everything happens too fast to be trying to keep your elbow down, flatten your top wrist, lag the clubhead, transfer your weight, whatever whatever.
I've no argument with working on some of these issues in practice. Perhaps we have swing plane issues or weight distribution issues or some other major fault that can be corrected. But once we are out on the course the only thing worth focusing on, as I said earlier, is rhythm.
There it is - the new rhythm method.