At my job we used to have to work 18-, 19-, or 20-hour shifts regularly. My record was 22.5. Really sucked. Thankfully we've made some policy changes so the worst I'll get now is probably 0830 - midnight, but it's risky.
Than go self-employed and you can do what you want but big no no if you work in healthcare, law enforcement and other critical sectors. Imagine bin men working 6hrs a day 4 days a week in a big city