On the Advanced Tab of the Library options, there are 3 settings to manage how collections are viewed. I wish there was a 4th setting to not display collections with only 1 movie. I like the mixed view of having movies and collections together, but if there is only one movie in the collection, they are often right next to each other so its kinda pointless. I only really use the collections for watching more than one movie especially if you want to watch them in order. I really like the feature in general, I think it just needs this little tweak.
I get that you can remove the movie from the collection, but it would be much easier to just have a global setting to ignore them as most of the collections come from the auto lookup. And then if you add a 2nd or 3rd movie later it will auto fix itself instead of having to remember you edited the collection field.