The 21-year-old has been in and out of the team so far this season, but registered a goal and an assist after returning to the starting lineup for United's 2-0 win over Watford at the weekend.
Scholes acknowledged that such performances have been too infrequent from the France international so far, but believes that he has the ability to score 25 goals a season in the future.
"It's only been flashes so far. We know he's capable of it. We've seen that he's capable of beating players and scoring goals, but we haven't seen it enough," he told BT Sport.
"He is still a young player, we have to remember that, and when you look at wide players they are always the most inconsistent on a pitch anyway. I think that will come with him, and if that does come and the confidence really comes out of him, I think he's got 25 goals a season in him."
Martial has scored seven goals in 24 appearances across all competitions so far this season.