When I wrote Catacomb Quest, the aim was to create a pocketmod by literally hand wtiting and illustrating the whole thing on an A3 page, then to reduce this sheet to an A4 page. As an idea, it worked reasonably well, but after writing up half of it I made a mistake, and then there was another mistake made towards the end of the manual illustration part of the process. These were all fixed up in post, using Photoshop, but I basically decided that if I were going to do this kind of thing again, I'd draw up the eight pages of the pocketmod separately, or maybe as 4 double-page spreads.
In this current spirit world project, I could re-use spreads that are common across different pocketmods, and if I stuff up a single spread I can just redo it rather than needed to redo the whole pocketmod. Yes, I can just make changes in Photoshop again, but this modular approach feels better for the project.
I think it might also be time to finish developing a font from my handwriting too... maybe that will be today's project.