Thanks for the answers so far. As far as I have seen, when a new version of a bigger bundle gets released by UVI, former purchases will generate a new voucher code. And with Vintage Vault 3 they offered the same introductory prices again a few weeks ago, for new customers as well as the different upgraders. So this would mean that if a sale should be around the corner, shortly after my current timed discounts have expired, it is highly likely that I would get a new voucher again? Which also should mean, that if one of my current vouchers should still be valid for a few days, it should get disabled during this new sale?
I don't get my head around it completely. And asking support isn't necessarily working out, because those upcoming sales are mostly kept secret, in my experience.