There is a tension between regularity of delivery and logistics. If you have things happening once a week, then you're asking yourself "which day of the week". It can't really be all the same day of the week (now you're looking at delivering 7x more packages that one day), but even if you distribute it all on a fixed day per address then people will still have times that they want things.

In a magical world post offices would have some sort of mechanism like just texting people that a package might arrive on a certain date, and maybe you can hit a button to request earlier delivery. Unfortunately the existence of that button requires restraint from the general population to be of any utility (and charging for the button press is a bit gnarly).

Perhaps in rural populations, people would be more reasonable though (especially if downstream of this system you actually had deliveries happen _when they are predicted to_)