Photo Keep Ratio to Strive for in Studio Portaiture?

I am a very statistical / numbers person and value others opinions and experiences. So I was curious..not being able to think of another way to term it.. what 'keep ratio' do you strive for when doing portrait photos?

I know it is a very relative question and can vary greatly based on the type of photos you are shooting as well as the intended purpose of the photos.

So I will perhaps throw out a test scenario that I can use as a baseline. If I have a model that is willing to work with me for a few hours to try a couple different poses, backgrounds, etcetra; how many photos do you tell them you expect to shoot? How many do you tell them you expect to actually be potentially usable. (especially in a TFP situation).

Again, I realize this is relative based on many factors (esp. skill level).. but what is a general base line ratio I should keep in mind. The one opportunity I had for studio portraits (my first) I took maybe 250 photos and the person liked about 25 (10%), though my opinion was I liked maybe 5-10 of them. (2-4%).

A prime motivation for asking is I want to learn, feel that I am providing people a service, generating something I like, but also not wasting their time nor mine. I am not charging or anything.. I guess I am just also sort of wondering what others expectations are of photographers and what expectations I should have of my own work (so I am not too overly critical of my own work.)

Christopher

I shoot more on location than in a studio where conditions are more controlled, but for me the main difference is in the quantity shot. With 8X10", we might have only shot one setup a day. The freedom of small format lets me go where the situation leads me.

The thing is, shooting is a process for me. Someone once said that if you have an idea, write it down & that frees up your brain to come up with more. Same for pics. Shoot anything to start. Chimp. Move around. Shoot some more. Chimp some more. As ideas come to you, shoot them. Chimp. Move around. Shoot some more, Etc. I usually "plan" on throwing the first 80% away. It's the process that counts. When you know you have it "in the can", shoot some more. Sometimes it's that last shot that really does it!

I did some "studio" shots here for my cousins daughter & 'cause I wanted to do a simple lighting tutorial. Total # of shots was about 70 in a 45 minute period. Follow the process...
Simple 2 Light Portrait Set-up