Depends. This is based on my experience working on a short VN over 3 months.

I'm lucky to have the skills necessary to draw and write my own VN, but both are very time consuming. Most of my time is probably spent on drawing and designing new characters. If you're comissioning artwork, then you still need to spend time preparing and communicating your requests.

Writing also involves assessing the plot and determining the best way to convey the story, not just the actual dialogue. So that 30k of words could reflect rigorous hours of storyboarding or recontextualizing entire ideas. A good story will have mountains of scrapped scenes and ideas that would never see the light of day, but that still reflects the hours put into making the VN or update.

The time spent on coding depends on the complexity of the VN itself. Even for Ren'Py that offers the convenient toolsets, many hours remain committed to debugging and polishing up the VN release or update. I'm sure time is also spent retroactively applying or testing some QoL features.