Hi CLA. Believe I sent you an email about this as well, but just wanted to reply here as well in case you saw this first. At this point the most advanced patterns of recurrence are those offered up by the “Custom” option. We’ve had a lot of requests for random recurrence patterns along the lines of what you’re noting and are planning on adding that in somewhere during the 2.1 lifecycle. Apologies we don’t have anything more substantive in the short term.
That being said, if anyone has found a way to hack it, CLA and myself would love to hear about it.