For a couple bad sheds, I intervened and got it off within 5 minutes. I only intervene if it's a significant amount of stuck shed, not for just a couple tiny pieces.
Put the snake in a closed tub with a slightly warm, wet towel for 20 minutes. Just leave them in there to soak up the humidity.
Take them out, and use your hand to firmly rub their bodies from top to bottom (head to tail). Their sheds naturally come off in that direction, and it'll just slide off.