I previously worked in banking (equity analyst) and no one at my level worked fewer than 12 hours a day during the workweek (in the office) plus 8-16 hours on the weekend.

At the beginning, I was working even more, at 14 hours/ day 6 days a week, then only 8 hours on Sunday. That seems unreasonable now, but I would expect to work 12 hours/day Monday - Friday if I were working at a bank now.

Of course, my position was different than yours, but I think you should be somewhere in alignment with your colleagues. If you have work to do, stay. When you are outperforming all your colleagues in less time, then you can leave when you want. The online idea of work-life balance and boundaries between work and non work isn’t real in practice when you’re starting out, especially in finance.

I know it’s challenging. Use this opportunity to learn about yourself and produce something you’re proud of.