Rook Endgame Pattern

Over the past four weeks I've temporarily switch from doing "Mixed Mode" tactics on ChessTempo to doing their "Endgame Practice" problems. The Endgame Practice problems are up to five piece endgames (using the five piece tablebase) where you can continue moving as long as you don't make a losing or drawing move. IE as long as you are still winning, your move is okay. But, you get marked down points for making sub-optimal moves.

The point of this endgame training is to 1) coincide with my study of 100 Endgames You Must Know; 2) give me more confidence when in a winning endgame but short on time; and 3) give me a better base of experience to decide whether to trade down into an endgame from a better position.

Going through so many closely related problems in a short period of time, I'm picking up on lots of little patterns. Here is one I see over and over in rook endgames.