Again with the idea that they should leave aside their initial projects to focus only on Radiant because money matters/I'm only interested in this game/the quality of this game exceeds their others...
Yes, logic says that working on parallel projects extends the deadlines for everything, but I think they know their own limits and they certainly laid out the pros/cons before starting the collab. In fact, a couple of months ago they said in a Patreon post that the consequences of possible delays due to working on multiple projects would fall only on their solo games because in Radiant both complement their strengths (as it says in OP, "Writing, coding, & game design by Sir Dammed. Artwork, graphics, & animations by Alorth").
In the screenshot that
Game Bond has put, the fact that the weather was against you and affects your work has nothing to do with having parallel projects. That Alorth was mentally affected by the loss of a friend dev, as he said there (Chatterbox, right?), has nothing to do with that either. And dozens of other things that will have slowed down development without being related by their solo games (for example, the transition from having full-time jobs to becoming full-time developers, which is not immediate btw). Some will take them as excuses but well that already depends on each one of us. And yet, even if these were really excuses, they would have nothing to do with the premise that having several projects in parallel is dragging them.