Riding exercise of the month: leg yield zig zag

Having recently been focusing on making sure that both of my horses are as supple as possible, I've been working on hard on the lateral movements. Shoulder ins, leg yields and half passes have become my go to exercises at the moment and I do vary between them, but my favourite riding exercise of the month has definitely been this leg yield zig zag!

(Image borrowed from here)

Instead of riding a zig zag where you keep changing direction, for this exercise I ride a leg yield for 3 or 4 steps and then ride forwards (and straight) for another 3 or 4 steps. And then leg yield over again in the same direction for another 3 or 4 more steps and repeat until you run out of space. The reason I love this exercise is that going straight after a few steps of leg yield is actually REALLY difficult. Both of mine expect to either carry on with the leg yield for the rest of the diagonal, or then to change direction but still to carry on with leg yield. Neither of mine think or anticipate actually going straight, and through this you can get total control over the horse's shoulders because at least I can't get my two to go straight without being in control of their shoulders.

Quick note - don't focus on how much the horse moves sideways, it's more about the quality of the steps with the hind legs and then the ability to ride them forwards after the leg yield. I praise the horses more when they quickly and easily go forwards after the couple of steps of leg yield, rather than praising them for a good leg yield as it's the better rideability and the suppleness that I am after with this exercise, rather than improving the leg yield itself (even though that does also improve with this!)

What do you think? Have you ridden this exercise before?