I just try not to think about it, and buy and play games I feel like playing, regardless of how long ago I got them.
I do set some restrictions though...mostly that I don't replay games (with exceptions), and usually choose to buy games from developers and franchises I like. I don't rule out other games entirely...I just don't make them a priority.
NNID: Zephyr25 / PSN: Zephyr--25 / Switch: SW-4450-3680-7334