Maybe every move in a rook ending needs calculation

Recently I've been playing vs stockfish the black side of the ending below trying to get an intuition of how to pay similar ones if I'm in time trouble or tired or some other reason I can't calculate on every move. 2 pawns up it is something like +5 for black. I'm winning only 1 in 3 and drawing 2 in 3. Looking at the analysis it is +3 to +5 (approximately) for black for a long time until I make a move that seems obviously OK (to me) without calculating then it drops to 0.0.

I'm coming to the conclusion that there are basic R&p endings we memorize. Beyond these, most of the moves in most of the rest are ''critical'' meaning the move needs calculation. (Of course, vs a person you only need to do it better than your opponent rather than a computer.)

And that R&p endings are not easy!