258 votesTom Ekeberg commented
Letting only actionable tasks be visible is the key with GTD (IMHO). Sequential projects are implemented in OmniFocus and Nirvana, and I can't see how the fact that it would complicate some people's workflow can be an argument against when all those people would have to do would be to only create parallel projects. Switching to project management software just in order to be able to keep non-actionable tasks in sequential projects, however, would unnecessarily complicate things. I, for one, would greatly appreciate the opportunity to create sequential projects.