I think what takes most of us the time is that we are learning as we go. Sure I pulled a head on another type of engine but not this particular VW. So it takes time to get it figured out. I know that the next time I do the same work it becomes production work. I popped the head off the car in a couple of hours last weekend in prep for hoping to put a new one on this weekend. Once we have been there and done that we get the time down considerably.
But if you only do one of these and one of those once in a while it takes forever.
DAS
Having to put it back together adds lots of time too, I've pulled a motor in 11 min, but it would have taken days to put the car together again afterward.
16 hrs for doing it like a shop, yeah I can see that. But I like to fetish the parts as they come off, take pics, daydream about how I can improve what I'm holding, drink a beer, daydream about how awesome the car will be when it's done, stare at the part some more, go online to find replacements, consult this site, clean something, paint something else, admire my work, try to find a tool, measure something, etc etc... It tends to add to the rebuild time.
Not exactly production work but very satisfying. I tend to do a bit of that style as well. Even at the expense of production.