How will anarchism minimize our workload?

I have heard from multiple people on reddit that we will work 15 to 20 hour workweeks? If that is true, how about jobs that require long hours. Example: Mental Health Workers (in asylums) if a Health worker works 4 hour shifts then it would need thrice as many people to fill in a 12 hour shift but if there were health workers that work 8 hour shifts then that would be unfair because everyone else would work 4 hour shifts (assuming they work 5 days a week) and then there's the psychological effect on them AND I WOULD LIKE some benefits because Holy shit i just saw a man playing with his insides.