The exact number is debated.
People's guesses on the ideal range generally fall between 55 and 80 minutes.
My personal opinion is 60-65 minutes is the ideal number.
Actually, the number is not debated, and it's not a guess. There is a pretty good empirical study out there showing that playing around 65 minutes, give or take 5 or 10, is optimal for game shape. 48 is definitely too few, and 80 is probably too much.
Last edited by GM-kozlodoev at 6/18/2010 5:53:47 PM
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."