I've been working on mills and lathes since a junior in college doing FSAE and have owned my own CNC mill since 2014. My main machine is a Haas VF2 with a UMC500ss on the way.
Run Volume sizes I work with are in the singles to thousands depending on the need though I prefer tens to hundreds.
If doing product development, I have a Master in Mechanical Engineering (MSME) and 15 years of industry experience to help your engineers effectively prototype focusing on what matters and importantly failing fast (IYKYK).
I was lucky in my previous role as a Senior Advanced Development Engineer to also be able to charge machine time to make my own parts on the side, nights/weekends. This was massively beneficial for me in learning creative ways to make important features, especially when dealing with off-axis work.