The transition process is different for everyone, and different for the same person who does it more than once. For some people it is smooth and for others it is not.
I met Frodo in Old Station and she said that the people who do best with the transition have something to go back to.
Some friends on the trail had to go back to work the day after they got home and they reported that it was the strangest feeling, as if the whole PCT hike had never happened and was only a dream.
Most people suggest taking some time to transition back. Things in the regular world will seem odd. Cars move too fast. People talk too loudly and about stuff that doesn't matter. I couldn't handle my type of work right away because it takes too much brain power and concentration. It's hard not to overeat. I've tried not to overeat and yet the pounds piled back on anyway. I think it's because on the trail your body thinks you're starving so no matter what you do, your body's going to hoard everything it can in case you start up again.
I hiked two summers in a row. After the first summer, I was reminded to bathe a couple of times. After the second summer I couldn't stop bathing it felt so good. I think that was because after the first summer, I didn't want to come home so I really didn't. I was home physically but in every other way I was still on the trail. Zero days until I could return.
After the first summer my feet were injured (that's why I went home) and I spent about 6 weeks walking around town barefoot to heal them. It actually worked. It took until almost the anniversary of when I left the Mexican border before I felt 99% back to normal physically. I met another woman who said it was about the same for her.
So far after this year's hike I am still physically a mess. Lingering injuries to my feet (different ones this time around) and generally I just hurt all over all the time. I went to the doctor and there's an elevated enzyme indicating muscle damage. Not sure what that means yet. I will probably be told to settle into my chair and drift off to the black hole of normal American life. A fate worse than death.
I'm left with a lingering feeling that this "normal" life is completely wrong, 99% meaningless and pointless and that most things people are so concerned about are not important. If the whole oil crash scenario were to happen, I would be cheering it on. Finally we can go camping permanently.