In my stints around Denmark and Japan (Computational Chemistry) you basically need ~1 top-tier or ~3 mediocre papers during your 3-year PhD.
In the US, PhD students in Computer Science and similar fields usually require 5-7 years to finish. They typically do not have MS degrees, unlike in Europe, where the expected graduation time is 3-4 years and they must have MS degrees.
You would be surprised how often there is a lot of low-hanging fruit. I'm good at asking "easy" questions that nobody knows the answer to, so a student just has to put in the work to get the answer. Many advisors don't give as much initial hand holding as I do.
So far my PhD students have taken 3-6 years to finish. Those that have graduated so far have finished with 3 papers (3 years), 9 papers (3 years), and 12 papers (5.5 years). The senior ones still in my lab (year 4 or 5) are on track to have around 3 first author papers in top-venues and about 9 papers total each. Their first author papers are in CVPR, ICCV, ACL, ECCV, BMVC, NAACL, ICLR, AAAI, etc.
1) 1 journal paper as the first author, so that they learn how that process (often is a review or perspective paper on their field, which goes in their dissertation)
2) 2 first author papers in top-tier machine learning venues (goes in dissertation)
3) 1 first author paper in a top-tier or second tier venue (goes in dissertation)
4) 1 collaborative paper with another PhD student (have to learn how to collaborate)
By the end, they have at a minimum around 4 first author papers and 1 additional paper. They can then turn these into their dissertation and these are signals to employers that they are competent scientists. If a student tells me they want to be a faculty member, we increase the numbers a bit (need at least 10 first-author papers to be competitive).
I also require that they be organized when we have our one-on-ones in terms of their experimental output.
That's pretty much it. It may sound like a lot, but I try to put training wheels on for the first couple projects and make them as tractable as possible because I fleshed out the project and found some low-hanging fruit, before I start trying to make them be more independent and drive the process.