Martin told manutd.com: "Sometimes you've got to play a position that you're not accustomed to for 90 minutes.
"Here it's more about expressing yourself, but then you've got better players around you here.
"No offence to the clubs I've been at, but you'd have to go a long way to find a club to match the standards on show here, even among the young lads.
"That's perhaps why it can be difficult for lads going out on loan, because here you're used to the ball rarely leaving the floor, and suddenly you can be in a Championship game where the ball's in the air for 45 minutes. It's tough."