If you use it with extreme care and not regularly it will not damage the leather. I carefully clean my leather steering wheel about every 36 months and protect it afterwards using a preservative (matt finish) I got from a local leather retrimmer.
I currently have a leather MK3 ST steering wheel which was in pretty bad condition. The previous owner used a gloss preservative on the leather and the stitches were molded because the car was exposed to the elements after an accident. After cleaning and preserving the leather the steering wheel is back in mint condition.
- theredfox likes this