I mash all my beers for 40-45 minutes. I ran a ton of experiments years ago, and determined that while conversion of starch to sugar typically occurs very quickly (15 minutes?), the attenuability, or simplification of those sugars to fermentable ones, takes a while longer. Mashing for 30-35 minutes was long enough about 50% of the time, but the other 50% of the time resulted in a very low attenuating beer (i.e., thick and sweet). 40 minutes is the minimum time I found on my system to get great attenuation every time without wasting time. If I want to, I can knock out an all-grain batch in 3.5-4 hours. This helps greatly to fitting brewing into my sometimes busy schedule. 60 minutes? Ack. What a waste of 20 minutes that you could be sleeping or whatever else. The only time I might mash for a full 60 minutes or longer is for the really huge beers >1.080 or where Munich is the base malt since it's got less enzymes. But for anything else that is "normal", 40 minutes is fine. Try it and see. Or if you're worried, go with 45. Still saves 15 minutes. And with that you could be saving $150 or more on car insurance, or whatever.