[throwaway3neu94]

Just following basic rules of thumb (minimizing current loop area, length matching, impedance matching through trace width, series termination, etc.) may yield a working device, but how do you learn from that?

At some point you're already applying all those rules of thumb, but how do you then actually measure what works and what doesn't so that you can improve beyond that?

It seems it is difficult to find resources teaching that, and also the equipment needed becomes very specialized and expensive fast.

[Kirby64]

The answer, unfortunately, is you can't. Once you start talking about USB3 or HDMI, the testing equipment to test it 'properly' as you would professionally gets to be easily $10k, and can be upwards of $100k depending on the interface.

[LeifCarrotson]

Those topics were the subject of the 3rd and 4th years of my EE degree (which was not cheap, and which involved some very specialized and expensive lab equipment).

But after 10 years in the field, I've sadly forgotten most of that and learned pragmatism instead.