When I got my car it had a really bad shake from 60mph up. Bad enough that I had to always keep it under 60mph. Balanced the front tyres and it got a lot better, but still there.

All the joints seemed OK but I fitted Powerflex bushes anyway. A little bit better.

Changed the tyres and now it's 99% right. Still a very slight wobble but small enough that you wouldn't notice unless you were expecting it.

So my take is that it's a combination of everything. Some combinations work, some don't and there might not be an obvious logic to it.