Not OP but with rook and king you make a box and shrink it while keeping your king next to your rook, and stalemate is all but impossible. With queen and rook you have to get the queen to a knight's distance from your opponents king and mirror their moves until the edge of the board, and at the end you need a slightly bigger L (4 squares) to avoid stalemate while your bring your king around. In the former the two pieces work together, in the latter they work somewhat independently (with a quirk at the end) until the final sequence of moves and therefore there is a slightly larger risk of error. In practice you should drill this regularly to mitigate the risk.