If the total range is 4c, changing the offset would just move the center of it. Instead of being 2c over the target and 2c under it, if you increase the offset by 1 degree you will still have the same 4c range, but your actual temperature will now be within 3c over and 1c under. Obviously if you actual median puck temperature wasn’t centered, changing offset could help fix that. But it would make actual temperature closer to the target one, i.e. it won’t make for a tighter temperature stability.