Usually SRO for say 10 to 12 years, 6 to 8 as a Shift Manager, so call it around 20 to 22 years into your career.
Last year I interviewed as a department head at a Utility. I ended up turning it down. I'd been an SRO for 8 years, total time commercial at 14.5 years, Shift Manager for almost 5 years.
I interviewed at another place, made the final two, then withdrew my application because I didn't really like the area.
Mike