Van 't Schip was a member of Van Gaal's first squad as a senior coach when he took charge of Ajax in 1991.
And the ex-Netherlands midfielder, now coach of Australian A-League outfit Melbourne City, said Van Gaal always had a good working relationship with young players.
"He was very organised and very disciplined, but also a good coach in instructing young players in how he wanted to play," Van 't Schip told Omnisport.
"He could really instruct in a way that the team bought into it.
"He was young still, but already you could see he was a good coach and that year we won the UEFA Cup, before I left for Italy and he went on to win the Champions League."
Van Gaal has blooded a number of young players at United with varying degrees of success since arriving in 2014.
Last season Paddy McNair and Tyler Blackett made 30 first team appearances between them, while this term the likes of Jesse Lingard, Cameron Borthwick-Jackson and most recently Marcus Rashford - who has scored four goals in two games since making his debut - have been called upon.
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"He's done it everywhere. At Ajax, at Barcelona with Xavi and Iniesta who came through the ranks when he was there," van' t Schip added.
"Even at Bayern Munich he started playing some players that had people thinking, 'how could he be playing those players?' but they became good first team players.
"Now you see it at United."
But Van 't Schip believes these situations were often the product of necessity, as has proven the case with Rashford - whose debut only came after injuries to Wayne Rooney, Anthony Martial and Will Keane.
"It's a nice story but it's the same as what he had at Ajax with [Patrick Kluivert]," the Dutchman said.
"Kluivert came in because there were some injuries he had done well with the youth, and started playing with the first team and scored the winning goal in a Champions League final and his career kicked off from there.
"But he's not afraid of playing young players and I think that's credit to Van Gaal."