Where do you live? I always get prime deliveries on time, and increasingly I get them same day if order before noon I think.

There were a whole selection of reasons for delay, including repeatedly giving the wrong address to the courier and continuing to use Yodel years after it stopped being funny. You are basically heavily dependent on your location relative to the dispatch warehouse, the courier's depot, whether your driver is overloaded, and whether your driver is a ring-and-run type.