How to aim for a favorable End Game from the Middle Game in Chess:

Watch what happens after the massive exchange. White takes with Rook.

 

Aiming for Rd7 !! White positionally finishes off Black.

Endgame Tactics & Why Every Check! Counts.

40. Ra4 - a5

41. Re4 - Kf6

42. Re8 - Rc5

43. a4 - Rc2+

44. Kf1 - Rb2

45. Rb8 - Rh2

46. Rb6+ !! - Kg7 ----- KEY MOMENT #1

47. Rb5 - R:h4

48. R:a5 - Rb4

49. Rb5 - Rf4+ ------- KEY MOMENT #2

50. kg2 - Kf7

51. a5 - Rf6

52. Rb6 - Rf4 --------- KEY MOMENT #3

53. a6 Rg4+

54. Kf3 - Rg1

55. b4 - h4

56. Kf2 - Rg5 --------- KEY MOMENT #4

57. a7 - h3 .... etc.

I consider those three moves by White in the below-designated positions as 'KEY' because the tactics of White ensured that Black would be kept off balance, exploiting the proximity of White pawns to the 8th rank to the utmost (in #2 and #3). In #1 White is checking the Black king before it goes on to capture the a5 pawn because the Black king cannot abandon the x-rayed pawn to his side - ensuring that the Rook check will keep the Black king confined to his area of the board WITHOUT advancing on against the lonely White h4 pawn holding the line.The key position advantage for White is the absence of the Black king on the Queenside. Each side has pawn majority on opposite sides of the board.
 ..

Black Rook puts pressure on White King

Who has more pressure? Going after weak pawn

Key Moment #2 (White Rook kicks Black Rook)

Key Moment #1 (Black King is forced back)

Key Moment #4 (White King asserts control)

Key Moment #3 (White Rook asserts control)