ive worked for small shops from the ground up, starting with mostly off the shelf hand tools and paper records, and moving into automated and well run repair businesses. The key i think is to find a company that realizes when they are squandering your potential and takes action before you're gone.
I went from brakes to suspension in 3 months and from there with consistent demonstration of talent, became the shop lead, then master mechanic, after 4 years. Im not so much a guy who twists oil filters anymore, but I'll still walk the floor and see whos doing what. I'll check our ticket queue to see what hasnt moved, or if parts in the crib need stocking. In my line of work we call it 'old timers.' guys who know and have the experience to guide, but dont necessarily care to leave the comfort of a comfy chair very often. Not a manager, but the first line of defense against having to talk to one.
I go out to fleets and take part in bids for maintenance jobs, not because Im a good mechanic, but because I know which mechanics I work with that are good for certain things. Im also known for bringing in a bucket or two of fried chicken for lunch on the weekends. I still have a workbench in the repair area, but my coworkers mostly leave weird parts I might enjoy or tricky problems to solve that nobody else has figured out.