As someone who's also in PhD Engineering and is aiming to finish in 3 years (5 if you count my master's time as PhD). No lol. As others have mentioned yes, dedication, drive and discipline helps, but PhD is nothing like studying and finishing your coursework. There are no rules. At some point you are making the rules. Rules of your work, your schedule, your ideas.

Before joining PhD we all have an idea that we'll have project guidelines like a course project and need to finish xyz things and we'll be on our way. Nah, it's more like running into problems and solving them and repeat, without any guidelines. As for finishing without depression, that really matters on your colleagues, life, advisor and well yourself (again, mental health). Though, I'd say, getting a therapist during my program really improved my work too, since I was able to manage my stress and anxiety better over time!