Agreed. My rule of thumb is: if it takes enough more than a second to figure out why I had the tab open, then I might as well just close it and re-open it if the need to have it available reemerges. It takes a lot of effort (several seconds and a lot of mental energy) to create the mental context that I need to make use of the tab. On the other hand, opening it takes a few seconds and requires little to no thought whatsoever.
So I just close them. In fact, having too many tabs open just makes it take longer to find the open tabs that I'm actually currently using.