I have recurring projects (update a particular CMS or write a blog post for example) saved in Drafts app files.
I call these through the shortcuts app. For recurring projects like blogging I have a repeating reminder in a SAL to run the shortcut. If a CMS needs an update which is intermitent I just add a task to again run the shortcut as and when.
I use Drafts to store them rather than shortcuts itself a) because it is easier to create them and make edits, and b) if I have to I can access them on a Mac as well. I tend to have a lot of regular maintenance type projects, storing them in OF clogs the system, although I do keep my weekly review “project” in OF.
I think the idea of storing things you do regularly and by habit outside OF, in my case Drafts but OmniOutliner is good and just referring to them rather than “burdening” OF with them is a good one. I have a single recurring OF task “complete evening check” with a link to a bulleted list in Drafts. I do not need to tick off this list I just use it a reminder of what needs to be done/checked, most just become instinct after a while, but the list serves as an aid.