Which Stage of A Chess Game Is The Most Important To Study?




Opening: Follow opening principles. The opening is the easiest part of the game to learn.
Middlegame: 1. Focus your attention on the opponent’s half of the board.
Focus on weak pawns and squares on the 5th and 6th rank (3rd and 4th if you’re black). The closer to the center the better.
2. How do I move forward and attack something?
a. Forcing Moves.
b. Force your opponent to defend, move back or somehow worsen their position.
3. What to do if there are no attacking moves:
a. How do I prepare to move forward to my opponent’s side of the board, prepare to bring more pieces into play and prepare to attack?
Endgame: 80% are rook and pawn endings.

All stages are important, but if I had to choose one to focus on, then I'd vote for the endgame. Having strong endgame ability helps a ton because then you know which endgames are likely to be winning for you (or drawn, or lost), so you can steer the middlegames into endgame positions better for you and similarly, you can steer openings into middlegames and then into endgames which benefit you. Knowing the endgame stage well gives you things to aim for (whether it be theoretical checkmates, or theoretical endgames).
One of the most foundational of these endgames to learn well is winning with a single pawn via king opposition; if you can learn to convert with just one pawn, then that's a big advantage to those who feel they need more material:

Im not sure if I have the correct GM that said this, but I believe it was Tartakower:
A mistake in the opening you can recover from.
A mistake in the middlegame will hurt you.
A mistake in the endgame will kill you.


Everyone will have an opinion on what is most important. But obviously knowledge in all 3 is vital to improvement. People should study what and how they want.
Which stage of a chess game do you guys think is the most important to learn and improve? If you don't know what I mean:
Beginning: The first stage of a chess game in which both players develop their pieces and castle their king to safety. There are multiple openings for White and Black, and many tactical advantages.
Middlegame: The second stage of a chess game, usually occurring after the beginning. This is widely considered the trickiest part of a chess game, as there is a lot of unpredictability and strategizing involved.
Endgame: The last stage of a chess game, occurring after the middlegame. A chess game usually shifts to the endgame when there are few pieces on both sides remaining, and usually, major pieces like the queen and rooks are the only ones left, along with some pawns.
Out of these 3 stages, which stage do you guys think is the most important one to touch on? Feel free to share your opinions under this thread.