the bigger problem with the geodisc, IIRC, is finding the center point of the tonearm pivot.
Missing that by a degree or so can and will generally give you a bit more unwanted inner groove distortion.
As we go to (move up the stylus chain of qualities) more and more severe stylus profiles, (Gyger, Fine-line, micro ridge, shibata, etc) this becomes more noticeable.
With conical or the more limp versions of elliptical (0.4x0.7), this can be less noticeable.
So I might use the geodisc, but then do a check on it with the paper protractor. And then see how much the paper says it is off, and then go back to the geodisc and finally see how much I missed the center point of the arm pivot.
A few mm of missing the center/pivot, is a lot, when it comes to inner grove distortion and human sensitivity to such.
this is where the bigger or better and more complex devices show their worth. The ones with an arm on them...to find that center pivot point perfectly, are the better units.
In the end, it tends to be all about inner grove distortion.