This depends a lot on stage of one’s career and where someone works.
The hours during Neurosurgery residency training are famously tough. Residents average between 60-80hrs per week or roughly 12-16hrs per day. That means one week could be 40 and another could be 100+. Most days are 6am to 6-8pm but taking call is 24-28hr long shifts. While that may sound intimidating, during medical school you become accustomed to working 12-14hr days and 60-80hr weeks between class, clinical work, studying etc.
The good news is after residency the type of job you take and the type of call (eg covering emergencies) you agree to take dictates your schedule. Most surgeons will start their day between 05:30 - 07:00am and finish between 03:00 - 07:00pm depending on whether you have clinic (seeing patients in office setting) or surgery.
The good news is that while there is no way to avoid the hard work and occasionally long hours, there are a variety of jobs to suite different lifestyles and priorities.