I think the wood you are cutting has more to do with how often you have to sharpen as well as how many times the chain touched the ground. Last summer I cut many green Hedge trees (Osage Orange) and could go all day and resharpen in the morning, then I started cutting Sugar Maples and had to sharpen three times a day. Same Stihl Chainsaw, bar,oil,and chain. I was told the Maples had a lot of dirt in the bark.