As an application designer, I'd like data this too. It would be great to get feedback on long pauses when in the middle of a process. For a real example, most of us suffer from the ribbon bar in Microsoft Office. What used to be a 3 second task is now a minute wasted trying to find the option in the ribbon bar, followed by resolving it in 3 seconds like before.
If they got feedback that the first time it was this slow, but then subsequently it took 2 seconds every time, great - we can chock it up to learning curve. However, I suspect they would find it consistently takes longer to poke around the ribbon bar and would come to the conclusion it sucks and we could go back to the perfectly useful menu system.
Conversely, I watch my 3 year old nephew pick up an iphone, swipe through two pages of icons, pick the one he wants, and start playing the game. No pauses, no hesitation. That seems to me they captured how (at least a 3 year old) intuitively works.
I do focus groups all the time, but this only lets me capture users at a specific point in time. If we could get this level of feedback from a built in usage library (without affecting performance), I think we could all do a better job of UI design that is intuitive.