The orthodontist I worked for put in serious hours well beyond many of the "crunch time" horror stories we hear in tech, typically arriving at her practice at 5:30am and leaving at 8pm (prepping the office, working on orthodontic appliances, case studies, paperwork), and working Saturdays as a part time Dean at the local dental school.
There were also state mandated continuing education requirements, the occasional emergency call, lawsuit, delinquent payments, marketing and sales for her practice, the occasional sales call from a vendor rolling out "Smart Brackets", and the need to manage 10+ employees and maintain professional relationships with other dental medicine practitioners for referrals and covering sick days.
She was incredibly driven and competitive, probably an outlier, but was also certainly a multimillionaire and an accomplished dentist.