Don't know how I missed this the first time around. I use a lot of start dates in my Omnifocus system.
I use them for recurring tasks the "start again x many days/weeks/months after the last time" types of tasks. I have lots of those, from vaccinations for various animals to getting irrigation set up and stopped each spring and fall and all sorts of bookkeeping tasks that need to be done on certain times for taxes. I also use them for things that I want to be sure I get to and review before a certain date. Say for things that I am considering going to like a movies or a party. I set a start date for when I need to reply, or buy the tickets or whatever. I have over 60 pending projects right now in my system but I am working on some as well that will restart once I finish the last task. I'd say I typically have about 100 or so projects in that category.
Oogie McGuire - Mac, iPhone & Omnifocus
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Paonia, CO USA