I'm not really knowledgeable of coding (hell, I fucking struggled with programming in C to make simple shapes with asterisks) but a friend of mine has coding gigs from time to time ranging from simple databases to full-on app development work for a business chain similar to Walmart (but he hasn't developed games so take that in mind).
Several of his coder friends usually take around 1 week more compared to him on developing similar projects and they're extremely competent coders as well. Seeing most of their workflows, it really varies from person to person and obviously the dev time increases the more stuff you do.
In the case of the Doc, he's pretty much doing everything (besides some of the sprites, as they're included in the RPGMaker RTP) and depending on how much or how little he knows about any of those and the workflow of each of them, it can substantially increase the time to do them. Can't talk about how he does each, as I don't really know if he streams any of his work and I haven't exactly been curious enough to look for it, so I can't tell if his workflow is somewhat efficient and/if other factors delay his advances.