The Dutchman has tended to remain on the bench for most of his 10 Premier League games in charge of the Red Devils so far this season.
“I am always on the bench because my philosophy is that we have to prepare our players to play the match and when you are shouting on the sideline, there is nobody you can contact during the game – especially when we are home at Old Trafford,” said Van Gaal.
“But at that time when I was at the sideline [against City], it was because of the red card for Chris Smalling and I had to readjust our system.
“That is why I was there, but normally I am never there.”
United host Crystal Palace at Old Trafford in the Premier League on Saturday.
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