I would like to add more color to this. 3 year PhD is very possible for a motivated individual at, what I'll call, the low end of R1 universities. That doesn't mean you cannot do good research (the OP is a counterexample) but that there is a fundamental difference between the program that the OP went to and top-tier universities. Think Harvard, Berkeley, Stanford, etc.
It is normally pretty easy to distinguish these programs because they focus a lot on the course requirements and that the thesis counts as a course. From the OP's institution, you can see that the course load is at least 15 courses and I would not be surprised if some students do 20 [1]. These programs are more or less an advanced undergraduate with a real independent research project that spans multiple years. Conversely, top-tier universities typically operate under the "publish 3 things and you have satisfied the thesis requirements". This cannot be explicitly written and this is normally difficult to ascertain online. For example, Harvard has similar requirements [2] but you can still find it for some departments [3]. The Catch-22 with this is that someone who can publish 3 things in 3 years can publish 6 things (or more) in 5 years which will greatly increase their academic job prospects. Thus, at top-tier universities, even the best students stay for 5 years at a minimum to start working the job market. You need to be at Dantzig's level to finish at a top-tier in 3 years [4]. To summarize, if you want to finish a PhD in 3 years, look for course-heavy programs and don't expect to get hired into academia.
Edit: I see the OP commented somewhere else that they published 3 papers. The OP is obviously a standout but I think most people have to be realistic that very few areas of research allow for publications in your first year PhD. For example, if you are doing research in LLMs, you are looking at a couple of years just to be brought up to speed.
In my experience in computer engineering in the academic systems of the USA, New Zealand, and Australia, a very large proportion of students will write their first paper in their first year. It is field dependent, but when I was a postdoc at a top US R1, 100% of the students I interacted with had their first paper in their first year. These even included students working on LLMs :-)
Also, top non-US universities often graduate their engineering students within 3-4 years of commencing, with 3-4 papers being a very common international expectation as well.
If you want to finish a PhD in 3 years and are interested in academia, in addition to following the path the OP has laid out you may also look to good international universities and then get your next 3-4 papers as a postdoc.
I appreciate adding data for the crowd but "a very large proportion of students will write their first paper in their first year" is simply not true when talking about the whole population. My department, albeit not CS but stats/ML, the first year is dedicated to doing courses and preparing for the qualifying exams. Some students would publish a paper. A few more might be coauthors with an upper year student (read, very little involvement). Pretty close to half would not even have an advisor until the summer. I studied at, supposedly to US News, a top 10 in the US for CS.
Typically, non-US universities have 3 year undergrads and 2 year masters prior to PhD. End-to-end, you are looking at the same time. There are, of course, exceptions. UK I think shaves off a year by integrating undergrad and masters.
Hiding the years or a PhD by doing an extended postdoc is barely the point of the exercise. The median time for a CS PhD in the US is 7 years [1]. Subtract 2 years for good students but add a year postdoc and I think you have a realistic 5-6 years from start of PhD to first academic position for the top decile.
I would like to add more color to this. 3 year PhD is very possible for a motivated individual at, what I'll call, the low end of R1 universities. That doesn't mean you cannot do good research (the OP is a counterexample) but that there is a fundamental difference between the program that the OP went to and top-tier universities. Think Harvard, Berkeley, Stanford, etc.
It is normally pretty easy to distinguish these programs because they focus a lot on the course requirements and that the thesis counts as a course. From the OP's institution, you can see that the course load is at least 15 courses and I would not be surprised if some students do 20 [1]. These programs are more or less an advanced undergraduate with a real independent research project that spans multiple years. Conversely, top-tier universities typically operate under the "publish 3 things and you have satisfied the thesis requirements". This cannot be explicitly written and this is normally difficult to ascertain online. For example, Harvard has similar requirements [2] but you can still find it for some departments [3]. The Catch-22 with this is that someone who can publish 3 things in 3 years can publish 6 things (or more) in 5 years which will greatly increase their academic job prospects. Thus, at top-tier universities, even the best students stay for 5 years at a minimum to start working the job market. You need to be at Dantzig's level to finish at a top-tier in 3 years [4]. To summarize, if you want to finish a PhD in 3 years, look for course-heavy programs and don't expect to get hired into academia.
Edit: I see the OP commented somewhere else that they published 3 papers. The OP is obviously a standout but I think most people have to be realistic that very few areas of research allow for publications in your first year PhD. For example, if you are doing research in LLMs, you are looking at a couple of years just to be brought up to speed.
[1] - https://catalog.louisville.edu/graduate/programs-study/docto...
[2] - https://seas.harvard.edu/office-academic-programs/graduate-p...
[3] - https://www.math.harvard.edu/graduate/graduate-program-timel...
[4] - https://en.wikipedia.org/wiki/George_Dantzig