I'm usually reading three or four which wasn't a choice, so I opted for 4-5 in the poll. Five is a little on the high side; that's the point where too much is going on and I don't feel as if I'm keeping up with all the books. I'm relieved when it drops down to four. Two, on the other hand, isn't enough to serve for variations in interest, mental acuity, and energy.
EReading didn't change me, it just made it easier to shift among books.