Quality can be improved with an OP-Amp used as comparator.

But filtering is needed, since the slow ramp of the RC will be modulated with any noise.

A constant current generator will definitely improve the precision, since a linear curve will keep the same absolute precision through the full range.

You can also do a dual-flank reading by measuring both the charge and the discharge.

But you may not need so many bits of resolution from the potentiometer, in which case this can work quite well - but you need to convert the measured time into a linear value.