Used it for years...use to do all my Motorcycle leathers....keeps them superb.
Have a custom built leather jacket, now 33 years old, used to treat it once, sometimes twice a year, for many years...the leather is still like new, but don't ride with it due to the age of the stitching.
My mate put me on to it...only thing he uses for renovating very expensive Chesterfield sofas.
A lot of guys in the classic car world also swear by it. ( That's where I
source it...usually cheaper ?).
If the strap is well dry....put it on heavy, paintbrush is good, and spread it about with a medium heat hair drier...and watch it disappear into the leather.
Leave in a warm place for a couple of days....polish off any excess, and repeat....you will be surprised how much it will take ?
After final coat polish, leave polish, polish, polish....result ...none sticky...none marking strap.... you only have to do this once....a light coat once a year, and it is likely it will see you out ?

I bought an old Barbour bag as part of a fly tying lot at an auction, the bag had obviously been put through a washing machine, and the leather work was like cardboard...so much I didn't dare bend it...four coats of the hide food and it is now fully usable.
Much better than Neatsfoot oil...and not the smell ! IMHO
Mel....