Wow, that's really long externship! When I did mine I was told that they are typically shorter, and that it's more like shadowing. I did very little, if anything. The administration at this particular institution (and my school) told me it was more for my benefit, to see if psychiatry was a good fit.
It sounds like your experience was much more comprehensive, and I imagine at the very least it would help convince prospective sites that you're serious about psychiatry. It seems like it can only be a good thing
Good luck, and I look forward to hearing from the docs on this forum re: your question