I've been offered interviews at all the schools I applied to, and been accepted to all where I have interviewed already. I only shadowed 2 doctors for a few hours each (so less than 10 hours of shadowing experience). I have a lot of job history, but none in optometry or medical offices. I was really only involved in one thing through college, but I was an officer.
I think it really depends on the person - be able to show what you did with your time. I certainly didn't have a lot of down time, but that's because I was working a lot while going to school. I also had really strong scores, which I'm sure helped compensate for very little optometric experience.
Also, to kind of downplay my lack of shadowing, I left it out of the "optometry experience" part of my OptomCAS application and just mentioned it in my personal statement. That way I didn't have to quantify the hours. I had researched the profession and talked to enough people so that I was able to talk a lot about the modes of practice and why I prefer one over another, insurance and billing issues, etc.
