This post is more for the new players than the great veterans that frequent this forum.
I know it may seem like a bit of a waste to study specific endgame positions, when they may not arise all that often. But, trust me, it's worth it. First of all, if you know what positions are winning and which positions are drawn, you will be better equipped to gear your mid-game tactics towards that endgame scenario.
Second, even if a particular position you studied does not come up, you never know when you'll be able to apply an idea you learned through studying an endgame position to a different position.
Take a game I just finished: Game 5678416
Now, around moves 33 and 34, I knew I had an advantage, but I just didn't see how to convert it. Then I thought of the lucena position, which, at the direction of User 134401 (who, out of the goodness of his heart, is helping me with my chess), I recently studied. Now, there was no lucena position in that game, but the idea of "building a bridge" with my rook to cut off his rook from my pawns came directly from my study of the lucena position. So, I played 35. Rd7 (it probably could also have been Re7, but the idea is the same). Now, my opponent might have been able to draw the game anyway with correct play instead of biting on my h pawn sacrifice at the end, but I never would have gotten to that position had I never studied the lucena position and thus been able to adapt the idea this this situation.
Edit: User 385712 points out (don't ask me why I just give user numbers instead of names. I just think the uid feature is cool 🙂) that 33... Ra4 is a draw because I have to play 34. g3 to save the h pawn and he plays Ra2 to cut off the King and I can't make any progress. I agree with this assessment. That's another useful endgame principle.