The Dane is yet to score in the Premier League.
Berbatov told Betfair: “Sometimes when you focus on the other parts of your game, you're not in the right position to actually score goals when the ball is in the box because you're tired after doing everything else. That's why I sometimes say that you need to work smart, not hard.
“It's very hard because if you don't score in a game and you also don't do any of the other stuff, the fans will say you're doing nothing and they'll say you're lazy.
"That's why some players compensate by chasing the ball and doing the hard yards because at least they'll make the fans clap and appreciate what you're doing.
“Eventually, as time goes on and you still haven't scored, it doesn't matter what you do. Goals for strikers are the most important thing."