I tend to rely on the Apple's UI guidelines. They have many hints that are applicable even for non-Apple apps. I remember Apple had a similar thing already back in 80s, which I found amazing.
Over time, iTunes has gotten very cryptic and undiscoverable in its features. I really wonder how users who're not well versed with computers even do anything with iTunes. Or maybe they don't even install it in the first place. :)
Cycle through apps using command-tab. Cycle through a few times. See how it works.
Now cycle through app-windows with command-` and see how that works .. completely differently.[1]
So yes, even the wizards can get it wrong[2].
[1] command-tab has a proper "memory" allowing you to command-tab back and forth quickly between the two most recent apps. command-` is just ... weird. It sort of preserves sequence ... until you let go ? and then reverses sequence ... or something ? 8 years into OSX and I still am not sure what the algorithm is.
[2] Not saying either is the right one - but they are both different, so one of them (as far as apple is concerned) is wrong.
Please explain the OS X iTunes UI to me. It's beyond awful, and it seems to get worse with every update.
If there were a death penalty for bad UI designers, and I were in charge of implementing it, I'd have the iTunes designers first against the wall.
My guess is that iTunes doesn't follow Apple's guidelines?