I can give approximate development times of each of my games:
Mari and the Black Tower: 9-ish months. It was my first game, so a huge amount of development time went towards learning how things worked. The game was originally planned for Android, so an even bigger amount of time went into learning how to get the game working on Android.
Knight Bewitched: ~3 months, though you could add an extra month to include updates and its eventual Android port around a year after its release. Development time was much shorter just from being more knowledgeable about MV, the Steam deployment process, etc.
My next two games, Finding Light and Knight Eternal, both had around 4 months of development time. My upcoming game, Roguelite 2 (I didn't mention Roguelite 1 as its development was a little messier) was finished in just two weeks (including playtesting, about a month) thanks mostly to using the systems from my previous games and upgrading them with more content and variety.
Development gets much faster and easier, in general, as you learn more about how to do things with MV, what plugins to use and what not to use (very important), and having a concrete direction for your game (as going back and constantly changing things will add lots of development time).
Getting into specifics, development time is hugely impacted by what plugins you decide to use and just how complex you want to make your game outside of plugins. In Bgillisp's case, it's not surprising his game took so many years as it's a huge game, probably having more content than all five of my games combined. That huge amount of content, while awesome, unfortunately comes with a much longer timeframe spent polishing that content and the most boring part of the entire process (IMO), playtesting.
Generally speaking, the more complexity you add to your game, the longer it will take to develop. Speaking from a commercial standpoint, complexity doesn't always (often doesn't, I'd even say) translate to more sales, which is why my games are relatively simpler than others you might see around here. I could've easily doubled my development time for each game by delving deeper into lighting plugins, Yanfly's action sequences with side-view battles, skill trees, item crafting systems, using an on-screen encounter system over random encounters, etc.
As for waiting on graphic and music assets, most developers use stand-in assets in the meantime so this shouldn't extend development time much. If you plan on using custom or specialized mechanics not present in any plugin already available, that will certainly add more development time.
Edit: Just to add on another example, consider the damage formula. Designing a system that uses complex damage formulas will take awhile, both figuring out what formulas to use and testing them for balance. Some developers even seem to feel guilty if they stick with variations of the "a.atk - b.def" formula. The reality is that A) the damage formula is already incredibly complex, it's just that MV takes care of 90% of that complexity, allowing you to easily fill in that last 10%, and B ) most consumers couldn't care less about formulas as long as they feel a sense of progression and the numbers on the screen get bigger over time.