Hi Aarika,
Thanks for the answer. This is the approach we have opted for as well - not because it works better than the suggested best practice approach, but because we like to have as uniform processes as possible. After all, expiration and notification reminders for fixed and auto-renew contracts are designed to be set and sent out via the 'contract term attributes', not notification tasks. That way, we will not have two different spaces for setting reminders which I believe will reduce complexity for the end user.
I like the fact that you are running a quarterly quality check - do you just pull a report filtered on perpetual contracts and calculate the difference between effective date and expiration date in order to see where action is needed?