Everything on this site about retatrutide comes back to one operational fact: the stock sits inside Metro Manila, so a metro delivery is a domestic courier run rather than an international shipment with a customs step in it. That removes the biggest loss mode in this category. What it does not remove is the run itself, and runs are not equal.
A parcel going to Muntinlupa crosses the southern half of the region. A parcel going to the far side of Quezon City crosses the northern half. A parcel going to Mandaluyong crosses the middle, which is where it started. On distance alone, this is the least demanding delivery in the National Capital Region, and for the least heat-tolerant compound I write about, least demanding is worth something real.
It also makes Mandaluyong the most forgiving district for the thing that actually goes wrong, which is a late collection. When a run is short, an hour of slippage is an inconvenience. On a southbound run it is a materially worse outcome.