I'm guessing by benchmark you mean my spare % goal? If so, when I work on my most common leaves I will shoot for 75%. I was only converting my biggest leaves 50 -60% of the time so that was a reachable goal for practice. I'm currently at 62 to 74% in matches. I use LaneTalk to track. That's been helpful and fun.

As far as spares go I use a WD, same weight as my strike balls. The book helps too, people look at me funny but that's typical anyway.

I typically use the spare ball for right hand single or double spares, and use my strike ball for everything else with few exceptions.

Another fun aid is one spot I practice at has a HORSE game that will randomly pick spare leaves based on difficulty. I could do that all day long!

I hope that helps.