The Dutch icon is confident Frank de Boer's men can cope with competing on three fronts, and they will learn invaluable lessons from the experience
The Dutch champions are still in the hunt for a third straight Eredivisie title, and have important Europa League and KNVB Beker ties coming up.
"That's just what happens when you compete on three fronts," he wrote in his column for De Telegraaf.
"Many people think it's a problem, but it is not. It gives younger players more experience and teaches them that every game must be played with that cutting edge.
"Footballers will discover that more is being asked of them mentally than physically.
"There are maybe one or two teams in the world that can dominate whilst giving ninety percent. In this case, 100 per cent must be given."
Isaac Cuenca will spend the rest of the season on loan at the Amsterdam ArenA from Barcelona, and marked his debut with an assist against Roda over the weekend, but is determined to improve.
"It was okay, there are enough for me to improve upon, especially physically. I felt a bit rusty, because I have not played in a long time," he added.
"I could hardly even remember when I was last in action. It must have been about eight months ago."