Yep, S&V-not_dead_yet. When I heard about switching (shading/shuffling and communicating), a light went on in my head immediately. It makes complete sense, right? Why would you leave half of the court open at any time?
I play doubles with a gal on my team for fun and practice. I've been calling switch and she still stands there, so then I have to run back. She missed the lesson with the instructor, but I've tried to explain 3 times. The first time she said, " I think we should just trust our partner." I said, "No, because we should've switched and you didn't." She still doesn't get it. Practice is one thing, but I won't play in a league match with her.
She's trapped in the mentality of "my side and your side". She doesn't recognize that sides are not fixed and can change, perhaps multiple times in one point.
Watch the point below:
Simon chips the return and approaches. The server lobs DTL. As soon as the DTL net man, call him Bob, on the Deuce court realizes that he can't get the lob, he should be calling for help AND he should be moving diagonally back to cover the Ad court.
Actually, Bob's first mistake was being way too close to the net just prior to the server hitting her next shot. It looks like he assumed she'd drive the ball. Notice that Simon reacts much more quickly [also, it's easier for the CC person to cover that shot because he can run diagonally rather than the DTL person who has to either backpedal, which is slow and prone to danger due to falling, or sidestep/crossover, which can be difficult, or turn his back altogether, and then you lose sight of the ball].
Simon, being the observant and quick-reaction player that he is, immediately sees what's happening and bolts to the Deuce court to run down the lob. But not even he can recover back to the Ad court to get the next shot. But if Bob had played the correct move, he would be defending the now open Ad court.
Ask your partner to look at the court configuration at 3:28: what does she see? Both players are on the Deuce court. Even worse, Bob is partially in the alley and Simon is headed off the court due to his momentum. What does that mean? That no one is covering the Ad court. Is this a good defensive configuration? Obviously not.
Seeing is one thing. Doing might cement the lesson. But she needs to be the one running so she appreciates the effort involved. Set up a point like in the video. You stand on the far court feeding. Have a 3rd person act as the DTL net man. And stick her in the CC position. Stand where the returner stood and lob over the net man and make her cross to get it. Then after she retrieves it, feed another ball [not the one she just retrieved] back to where she originally was.
Now re-run the play but have the net man play correctly by moving diagonally backwards to cover the open court. Before you feed the 2nd ball, tell everyone to stop and point out how much better this configuration is vs the other one where both her and her partner were on the same side.
And then see if the light bulb goes on.
Here's another:
In the first 7 seconds of the rally, there are 2 switches.
The need for this happens all of the time. Your partner is just not observing it.