The Red Devils failed to finish in the top four of the Premier League last season, and as a result missed out on qualification for Europe's top competition for the first time since 1995.
Van Gaal feels that the tournament provides the best way of evaluating the talent of a team.
He told reporters: "When you can play the Champions League, you can compare yourselves as a team with the better players, with a higher level.
"I think when you are in the Champions League and it's going well and you beat opponents, you're getting in a flow and then it's not so bad to play all the matches. Maybe in my first year here I will have more chances to train with my players. That's probably better than all the matches, maybe.
"But at the end of this it's always better to play in the Champions League and all the cups and play all the matches, because you can compare yourself with higher level opponents."
United face West Bromwich Albion in their Premier League clash later today.