I too use the On Hold-feature to quickly and easily change a project from being an active project to being backlog or someday/maybe. They way it works is that I have my context lists set up to show me Available actions so anything On Hold doesn't show up.
My someday/maybe projects are then also in a separate folder so that I don't have them mix with my active projects. Backlog projects just stay in the normal project lists.
My backlog projects are typically projects that I have already started and that I intend to complete within a couple of weeks but that I don't have the bandwith to work on at the moment. So that is in principal the subset of someday/maybe projects that I want to review more often than the rest.