I suppose I will represent the other side of the spectrum. I come from a program that has always been a 4 + 1 for those coming in with a BA, and still pretty much is, though I wonder if we will become less competitive in the future for internship just due to lack of time in graduate school. I have pitched moving to a 5 + 1 to the faculty, but their position was "why do that when the students are already achieving what we want from them in 4 + 1."
So what can you do in 4 + 1? In year 4.5, I am halfway through a very research-heavy clinical internship, have seven publications (but only one first authored, several others are in the pipeline but it is sometimes hard for faculty to keep up with non-milestone projects given the timeline), and have defended my dissertation. What haven't I done? As I mentioned, I only have the one first-authored publication, and I have never applied for a grant, which I think has hurt me on the job market.
As for the job market, I applied for faculty positions at research I universities this year but only received one on-site interview. I think an extra year would have been very helpful for being competitive right out of grad school. However, on the flip side, should the one interview not work out I will take a one-year post doctoral fellowship that pays significantly more than a graduate stipend (3 times more in my case), so I can't really complain as I get the same benefits with much greater pay.
Overall, given the current internship landscape, I think 5 + 1 is ideal, more is not a bad thing as long as you can live on the funding, and 4 + 1 is fine as long as your students are matching. There are always post-docs, where you get paid better than you do during your grad school years, so why not try to get an internship as soon as you are competitive and then move on?