Roy Gandy has always claimed VTA adjustment is unnecessary. But if you try and fit some non-Rega carts to a Rega arm you'll see that's not necessarily true. Not all carts are the same size and profile, which is why people end up using shims to get the arm into approximately the right position.

VTA adjustments *do* make a difference IME, but I don't bother adjusting it for every record as some people do, just get it right for an average thickness pressing and forget about it.

-- Ian