When I started out, I believed that working harder meant getting ahead, so I often stayed late, skipped lunch, came in on weekends, and even covered for people who weren't there because the company wouldn't hire enough staff. Do you know what I got in return? More work, and nothing else. No promotion, no bonus, just a growing pile of responsibilities until I eventually burned out and had to take leave.
That is why my advice to anyone early in their career is simple: don't do it. Do your job well, but do it at a reasonable pace and don't sacrifice your health trying to compensate for problems the company created. If they're understaffed, that is a choice they made, and they should be the ones dealing with the consequences. Don't protect them from their own bad decisions by wearing yourself down.
And the truth is, they are not going to fire you for working normal hours, because if they did, who would be left to do the work?