Logic refactoring

This is a nice-to-have, not a blocker, but it would be nice to go through our logic and clean it up. The Docassemble folks are working on a new paradigm where we can put all our logic in one place, as long as we are careful to avoid setting any variables in that logic. We should look into that new paradigm (the Docassemble slack channel is a good place to start), and then implement it here to simplify our logic.

Start by reviewing the new logic paradigm discussed by the Docassemble folks, using the Docassemble Slack channel as the issue's suggested entry point. No files or tests are named; done would mean agreeing on the approach and applying it here to simplify the logic without setting variables in the centralized logic.

Written by the indexing model from the issue text.