Part of my selection process is to bring my calipers with me. A hide of 1 to 1 1/2 oz. can be no thicker than .035. Being picky of what you buy helps in the long run. I can get 8 to 12 good pieces from a selected hide. The thinner the hide the better it is to stretch. Too thin however runs the risk of tearing the hide when stretching. Each piece of leather I cut from a hide is approximately 6X9 inches in size. If I have a BIG pad to cover I will cut a larger piece of course. I too use Barge Cement.
Good advice on the leather selection and thickness.
The stretch of the leather can be improved a great deal by soaking it in a mixture of 50% water and 50% rubbing alcohol for 10 minutes before stretching it across the recoil pad. I let the hide dry for 24 hours after stretching, then glue it to the pad via contact cement such as Barge. I owe the water and alcohol tip to Jack Rowe who immigrated to USA from UK.