Different people work in different ways. It's his time to spend how he chooses. Personally I don't like working on more than a single game at any one time for the reasons you have stated. I have heard similar complaints before when a game is not being rapidly developed. It's something several people like to complain about, but it doesn't make any sense to me for the following reason:
Nobody would complain if a developer has a wife and kids and likes to spend time with them away from developing a game.
Nobody would complain if a developer is getting a higher education attending college taking time away from game development.
Nobody would complain if a developer is working a normal job on the side to pay the bills.
Yet, a lot of folks make a fuss if a game developer works on more than 1 game at a time?
Don't forget that game development, even on an indie level, is a process that can take YEARS. And CG filmmaking, which shares a fair bit of similarity with the creation process of visual novels, can also take a very long time. And those have teams of hundreds of people working on them.
An indie project with one person working on it should be expected to take a long time to complete. And many don't seem to appreciate all of the behind the scenes happenings as you mention.
The lack of patience is killer, and it's definitely an added stress on the developer. All the complaining will do is cause the update to take longer.
Source: I work in the entertainment industry, from video games to film/television.