I have a project that is done twice annually, so making it a repeating project comes to mind—however it is not done every 6 months; it’s more like 2/15 and 9/15 (7 and 5 months intervals). I don’t want to create two separate repeating projects with a 1 year cycle, because when I do the project, I inevitably make changes to actions, etc. that I want to remain in the next instance. I’m not seeing a way to accomplish what I’m after in the repeat inspector.
I’m currently setting the repeat interval to 6 months (with a due date of 2/15 for the upcoming spring repeat), and the first action of the project (with a tag of “OF” (my shortcut for OmniFocus)) is:
“When this project is complete, change the next instance due date to 2/15 (if the current project is complete in the late summer/early fall), or to 9/15 (if the current project is complete in the spring).”