The Dutchman has used the entire 26-man travelling squad in the four wins against the LA Galaxy, Roma, Inter and Real Madrid in the USA before he looks to add to the signings of Ander Herrera and Luke Shaw.
Van Gaal says he is close to making a decision on which players he wants to keep and which can leave, with the likes of Marouane Fellaini, Javier Hernandez, Shinji Kagawa and Wilfried Zaha facing uncertain futures.
"I shall make judgements. After this tour I shall make judgements because I let all the players play and I know now more than before the tour," Van Gaal told reporters.
"But also it's a little bit soon to judge. I football you have to judge because you have to give a chance to the player to make a transfer when I see that his prospects to play aren't so high.
"Then you have to say it. And you have to say it in advance. When it is August 31, it is too late. So I shall say to the players what I think after this tour. To them, but not to you."