I purchased my pro4 i7 less than a week ago and I was fully aware of the battery drain issue during the purchase. I tried 3 different methods to check how much the battery drain happens during 10hours of shutdown
1.) First time I shutdown my pro4 and immediately closed the typecover with it. After 10hours, Next morning the battery was almost 30% gone.
2.) Second time, I shutdown and immediately detached the typecover. After 10hours, Next morning 0% battery drain
3.) Third time, I first turned on the backlit on my typecover. Then I shutdown my pro4. After the screen went black, I clicked on the mouse pad and saw that the backlit was still on indicating the typecover is still charging itself. I waited for another
30seconds and the backlit went off indicating the Pro4 is now completely shut. After 10hours, Next morning "wallah" 0% battery drain.
I did step 3 two more times and same 0% result indicating that even though the Pro4 shows black screen on shutting down, it still hasn't shut down completely and hence waiting 30seconds before closing the type cover is a good option to make sure the shut
down process is complete.
I also did "Crtl + L" and waited for 10hrs. This time it was 6%-7% drain.
The boot up does not take more than 5-8sec so I am fine with shutting down my pro4.