Short answer: Yes!
I normally come back from a trip or similar and have a few hundred pictures to process, so I work through them over the course of a few days before I export them. I always though save all my RAW-files so it's easy to pick them up in LR again. I often find myself wanting to work a little more on my best pictures, could be exposure, WB, saturation, just about anything. On the other hand, I am still a novice using LR so I'm on a steep learning curve which actually means that when I look at pictures I processed a couple of months ago I only see crap compared to what I can do today.
For me it's the same when it comes to writing (where I am more accomplished than in photography) I like to re-work my articles over and over again to get them exactly where I want them. I guess this is how it goes in the creative field. Doing photography almost exclusively for myself I have the luxury of not needing to meet deadlines.
For you I would think it is different as you have to submit your pictures towards a deadline. I guess you and other pros will have to settle for a level that will work for what the customers expects.