The reason why we ship every 80 days (instead of every 90 days) is to compensate shipping delays. We are shipping from a centralized warehouse to all European Union countries and we have experienced that sometimes postal companies do take up to 2 weeks for delivery (even shipping to the UK sometimes takes longer than it should due to ineffective loops in the postal systems). Also we believe it does make sense to accrue some backup capsules/supplies over time in order to compensate for such shipping delays when they happen or to compensate for other losses.
We can't really change the billing/shipping cycle to 90 days due to technical reasons. However, we can skip a quarterly shipping/billing cycle at any stage if wished, i.e. once you have accrued enough backup supplies (to feel comfortable with skipping a whole quarterly billing/shipping cycle) just let us know.