Hernandez scored 20 goals in his debut season in English football following a move from Chivas de Guadalajara in 2010. He collected a title winners' medal, earned a starting place in the Champions League final at Wembley and won the Sir Matt Busby Player of the Year award.
His second season wasn't as prolific with a return of 12 goals. Sir Alex and his coaching staff quickly identified a need for an extended rest.
"When we examined his previous summers the answer was there," Sir Alex told reporters on Friday. "You can play too much football, there's no doubt about that."
Chicharito is pencilled in to start at Norwich but has also proven his credentials as an impact player.
"Some players are good substitutes but others are better when they start games. Ole Gunnar Solskjaer would watch a game quite closely and concentrate on what was happening on the field. Maybe Chicharito is the same, it's difficult to say."