OK, with doing it in hundreds at a time, I'm down to around 7 minutes per box. That makes 9 hours' work, which is still a lot, but doable. I might see if I can arrange a bundling party tomorrow night to get some done faster
We do have some location information @geeksareforlife, but we don't have enough density of it to make that sort of location targeting useful, unfortunately. We're better off hitting up friends and neighbours, I think.
@Lewis_Sturrock my current advice is to make well-counted reference piles, one of 50 and one of 100, and measure your bundles against those. Do 6 100s and 2 50s per box, for a total of 700 per box. You'll get to a point where boxes don't have the full 700 in them as it has to be split by delivery office, but most of them will be full boxes.
It's a lot quicker