First of all: I didn't base my calculations on my personal play schedule. My play schedule is erratic - which can be plainly seen by an analysis of my posting times. I'm an insomniac and might be up 24 hour straight one day and 16 (or 18 or 20 or...) the next. I may sleep 8 or 9 or 10 or 6 or 4 or 5 hours at a stretch - whatever my body and brain let me.
I could probably count the number of times I HAVEN'T collected from my 8 hour buildings 3 times a day on my fingers. There have actually been a few days I've collected them 4 times in one "day".
Yes, there are people who routinely stay awake 18 hours or more and sleep 6 hours or less (or at least claim to while they fall asleep every time they sit down and blink). But that's not MOST people. MOST people are awake 16 hours and sleep 8. So that's what I based my calculations on: being awake 16 hours and sleeping 8 (or more accurately being awake a little over 16 hours and sleeping slightly less than 8 since that's what would be required.) I also extended my calculations to cover 2 such days for a more accurate result.
Here's my chart:
http://drive.google.com/uc?export=view&id=0BxVjXB2JwaLxbzFfbzBrSzd6WlE
And now I must be off to bed since I've been up over 20 hours today and I'm starting to get sleepy.