I think your timetable on PHN is inaccurate, both from my research and my personal experience. If one still has the pain from shingles after 2-3 months, then the diagnosis of PHN is usually given. Some people do recover "fully" but from people I've gotten to know, there may still be very minor issues if they over-do it. That nerve may always be a bit off, but it's not like it was previously. But realistically (DARN, what DID they do with their SPELLCHECK!!??) that to me is a VERY good outcome.
I'd say a decent percent, I'll say 30-60% get some relief or quite a bit. I really don't know the actual statistic, but that's my rough guess. Some notice almost no improvement, despite various treatments. I think that some areas, such as the face area are more problematic, other areas seem to be a bit more likely to improve.
My story? I got shingles almost exactly two years ago 10/26/16. By early December the doc said it was PHN (which is a bit earlier than some felt). At first I believed that I had almost no improvement. But after about 4 months, I realized that was a tiny bit of improvement. I couldn't measure it in days, but I could measure it in weeks or months. ie. what hurt a lot two months ago, now hurt less. I focused on that, but still wasn't sure how much better I'd get. Oh, my PHN is in my left back/chest area. By July 2017 I realized between the pain and the gab side effects I couldn't work. It was only part-time, 10 hours a week, but I was too miserable and befuddled to be effective.
Long story shorter, about April I realized there was quite a decrease in the pain compared to a year before. I still had problems, but the pain scale numbers were lower. In June I had a whole month, almost pain free! It came back a bit since then, but is much, much better than before.
However, I'm tapering from gab, and every two months (I drop 100 mg and found the withdrawal was too miserable after month months) I have increased pain and problems from the taper. The meds are causing me more problems than the PHN. But now that I've decreased the gab from 2700 mg in January 2017 to 700 mg in October 2018, I've gotten more of my memory and cognitive skills back. There are still problems but I wonder if once I'm off gab if the pain will be gone too.
That was the LONG answer, sorry. That short answer is YES, one can get back to their normal life and have almost no residual PHN, but the odds are better of this if you noticed improvement in the first 3-4 months. Even any tiny improvement shows healing.