The important thing to remember here is that most auto leather is what is known as finished leather. It has a pigment coated surface with a clear coat finish. 'Conditioning' this type of leather is not only a waste of time but impossible. All the claims of nourishing, feeding, extracting dirt are nonsense and only a marketing ploy.

'Conditioners' especially oils and waxes cannot penetrate the finish on the leather and will only remain on the surface which will actually attract more dirt which is what you are trying to avoid.

The key to keeping leather in good 'condition' is to keep it clean. Do this by using water based cleaners on a regular basis and a leather protector which will protect the finish and inhibit its breakdown by dirt. A leather protector will also help in the cleaning process.
Dry leather requires moisture. The oils and fats which are reintroduced into the leather during the retanning process are sealed in and do not dry out or escape so do not need replacing (impossible to do anyway)

Hope this helps