The trick is that double braced support. I’ve never played on a single X stand that didn’t have some movement. The best that I ever found was the old Invisible angled x-stand (very rare, the double tier vertical one was much more common) which was angled backwards so the weight of the keyboard stressed the stand into rigidity). Tried to find a picture, no luck!

But I still hold with the basic ‘leg at each corner’ approach, which permits no motion whatsoever. https://www.sweetwater.com/store/detail/...-keyboard-table Add an extra tier, still rock solid..!