<p>
It happens, but rarely. A 1-year MS is pretty difficult, 2 years is typical and 3+ more likely than 1. On the PhD, 2 years is really only possible if you do MS/PhD at the same school. Otherwise 3 years is usually the minimum. And yes, the way you do it is to schedule wisely, work very hard, make no mistakes, and have a little luck.</p>
<p>Back to the original question:
It is up to you, your advisor, and your program. The program will have certain milestones you have to meet, and often minimum and maximum times that must be met. Your advisor will have to formally or informally support you at these various milestones - if your advisor doesn’t think you should get the PhD, you don’t generally get the PhD! And, of course, much of it depends on how hard you push to get out.</p>
<p>It is rare to see someone go from BS to PhD in 4 years or less, 5-7 years is pretty typical, 8+ years is frowned upon in engineering. Some advisors will push you to finish quickly, others will want to keep you around a while, and most departments don’t really care how long you take so long as it is within the guidelines and so long as you have your advisor’s support!</p>