3 or 5 Years?

I'm a part of a group that helps support PhD students both within my university and in other universities. Recently a question popped up about how long it should take to complete the PhD requirements. I've had this discussion before. When I started I buckled in for five years knowing that that is how long it typically takes students in my program to earn their PhD.

If you're goal is to just get the credentials than it shouldn't matter. If your goal is to actually become an expert in your field, than it might be that the longer course of study is better. 

That being said, i don't know if just "years" alone is the best gauge. How many credit hours are involved? How many classes? I'm taking a course of study that generally takes 5 years to complete. I come in with a masters with transferable credits so that helps accelerate some things. 

My boss wants me to finish in 3 years because he wants the credentials for marketing purposes. My major advisor has said, the goal isn't to be done in 3 years . . . the goal is to be a genuine expert in the field of study. That takes reading and time. I'm taking multiple courses per semester and overloading a bit, but I'm not sacrificing knowledge transfer or reading. It's a bit of a balancing act. 

I think the goal is expertise which goes beyond just years of study. Take a look at the program and the credit hours and classes rather than just years to complete.