I've had this feature on many tables but only used it to lock in the correct speed as best as possible visually using the typical complementary strobe light visual speed indicator features, not to tweak the speed otherwise.
If the records did not sound "right" when the proper speed was indicated, then there was a problem with the table and I would either have it fixed or replace it.
If the records did not sound "right" when the proper speed was indicated, then there was a problem with the table and I would either have it fixed or replace it.