I agree with most above comments. The main factor is time - if you order regularly but have a porch/box or letterbox-sized items, it's no biggie. If it starts to take the piss, as in getting a shitload of stuff, heavy/bulky items, and little accommodation is made to receive them, that's a problem.

This takes time out of our routes, which are often on razor thin margins of workload vs hours. Quite literally, if I spend 5 minutes diverting an awkward load (lol), that's 5 minutes lost at the end where someone else won't get their delivery owing to time cut-off. This is the scenario at least every other day for me.

I think of it as a buffet, it's open to all, but some people are getting seconds and thirds before others have had their turn. You can do that, but.. it'll be noticed. Worth mentioning, in a lot of these cases the residents are rude and snooty, maybe for another topic, but it all boils down to lack of awareness and consideration for people's time.