I consider myself on the high side of the fast scale ...
I played in a tournament this past weekend and was waiting for a match to finish that would decide whom I played next. Race to 7 on fairly easy 9 footers (GCIII). Went hill-hill ... Anyways, they took 2 hours and 10 minutes !!! ... was painful to watch and wait out.
So, up comes my match against the slower of the two slow players. 20 minutes later I had won 7-2 ... he made one 9 of break and one 8 - 9 "runout" when I hung an 8 ball.
So, doing the math for that match;
20 minutes = 1200 seconds / 73 (balls, 8 racks + 1 9 ball) = 16.43
But, if you consider racking took about 20 seconds (magic rack), then the total time would be in the 1020 range, which gives 13.97 seconds.
So, about 14 seconds a shot... which seems totally accurate to/for me.