[jusob]

I wanted to share my experience. I was a foreign student doing a Master in the US, with several other schoolmates. 3 of them decided to pursue a PhD after their master. We all understood that a Master is done in 2 years, a PhD in 3 years. So they all completed their PhD in 3 years, not a month more. But I met many students, in the same field, some with the same advisors, who were 5+ years into their PhD with no end in sight. I think a lot of it came from the state of mind. My friends had a very specific time lime to finish their PhD in 3 years and they followed it, pushed their advisors when needed, etc. There was never any doubt that they would be done after 3 years. Whereas others started an open-ended journey with no clear goals.