Placing Ground Vias To Improve EMI
Step one: Show one solid proof that this helps in a predictable way. Not just some textbook, but real solid proof. And I can tell you: If that works and really does something measurably good in a predictable way, there will be plenty of solid science to back it.

Step two: Realize that it may not be worth your time.

PS: A good low impedance PDN (power distribution network) works in a predictable and measurable way. And so does other things like shielding. If done right.