If you divide by the angle the yo-yo is “tilting” off it’s y-axis, then your formula postulates that most players will have a sleep time of 0watts/degree. Not only does this not have any relevance to the rpms (which ultimately could calculate the sleep time), but obviously the formula contradicts the known fact that a straight throw will sleep the longest. I’ll just ignore the last part, lol. There’s the long answer.
The short answer is:
See what happens when I over-think stuff? I give you a long explanation instead of yo-yoing. Sad times.