Did you put all 30 pictures in that album? and 20 left on their own?
Or are you talking about one of those view things that Apple provides, like Trips or Memories? Those are cute things Apple provides as a gift--you enjoy them or not, but you can't expect too much. Apple tries to collect pictures you will like and exclude ones that aren't so special-- but Artificial Intelligence is not really intelligent. It thinks you like pictures of people, for instance, so there will probably be more people pictures in a Memory than landscapes, even if to us the landscape was the best part. As with any gift, you politely take it, say Thanks, and after you're through with it you put it away where it doesn't bother you any more.
I use some of these things to remind me to go back to look at Thanksgiving 2017, for instance, and collect the best pictures and put them in an album that has what we want in it. It's the albums that we make for ourselves that are special.