Unless the Holy Ghost moves. 
If the artists are good, then I don't mind a 3 hour concert

true. I don't mind a 10 minute praise break, as long as that includes the praise break reprise(s).

And yeah, I can take a 3 hr concert if the artists are good, energetic, and dynamic AND there's NO fluff between artists. Keep it moving. I don't want to wait 5 minutes in between for the next group to move, line up, proceed, set up instruments, and then hear the director exhort (read: STALL) for the next 10 minutes before they sing....
Bottom line for me, it could be 2 hours or 4, but when I start looking at my watch, you have lost my attention.