Terry, 32, will be missing from Sunday's FA Cup semi-final, the latest in a string of high-profile games the defender has not started under Benitez.
Benitez said: "With his age, he has more experience and his understanding of the game will be better but you have people coming that will be faster and they will be stronger. But still he has a lot of ability and he can do well. But it will not be two games a week, carrying on playing, because you have more competition [in the squad].
"His age  is fine. It's not a bad age. But you have someone coming with 25 and the other with 28 and they are pushing and pushing, so you have to compete. And this is the main thing: if you play two games a week it's not easy to keep at the level. In a normal team, fine. But in a top side where you have to win every game, it's not easy.
"The problem with John is when we came here he was injured and it took too long to find a solution - not because we didn't know, as the doctor here is really good - but it was taking time.
"And afterwards everyone was expecting him to play. But you have good competition here, you have good players. At this time Gary Cahill was doing really well, Branislav Ivanovic was doing well, David Luiz is doing well, too.
"So he has to accept, everyone has to accept, that we have a good squad and when we have a good squad, you have to compete. It's part of the game if you're in a top side when you play so many games."