I realized this when I was looking at my collection, which has had some heavy purges over the years. Most of the games are games that I want to play more, games that have proven themselves. Some are games that I haven't played yet but I don't want to get rid of until I've found out if I want to get rid of them. (Fewer of those than there use to be)
But there are games that I have played, enough to know I am interested in them, but I haven't played them enough to really grok them. I know they are fun but I don't have a fundamental understanding of them. (Which is completely different than being _good_ at a game or even a deeper understanding of them)
I'll be honest, a big part of this comes from back when I was buying games faster than I could play them. Play one game and move it onto the next. That did teach me a lot about learning rules and teaching games but it was terrible for replaying games.
The way that I look at games has changed a lot over the years. Being a member of the cult of the new was exhausting and inefficient. At least for me. Hey, it probably is great for some folks.
But I did learn a lot about games during that time. And, when I look at my shelf and see games like Colossal Arena or Memoir 44, I know that I picked up gems that I haven't even begun to appreciate properly.