One issue with the way workflows are currently triggered:
Lets say we created booking reminders for 1 year, 6 month, 1 month, 1 week and 3 days prior to the start of the course. Currently if a booking is made 1 day prior to the start date, then all of these reminders would trigger at once and bombard the user with emails.
... I think you would all agree, this is far from ideal!
A solution for this and other workflow issues or other filter issues, would be for more advanced filters, that would include operators such as:
Using the above scenario, you could build something like:
1 week reminder: if current date is greater than (course start date plus 7 days)
1 month reminder: if current date is greater than (course start date plus 1 month)
I'm sure there are many more use cases for such filters!