[donor20]

That's not totally true. They do support scheduled shipments for folks like Apple where the items are shipped but held to insure basically a global US delivery date for most packages in the batch. But this is pre-planned, normally at worldport etc.

[sokoloff]

UPS does indeed run a third-party-logistics (3PL) business, but I doubt that's able to be cannibalized to act as a buffer tank for their parcel business. (I also suspect that UPS's 3PL business is also booming this year. They reported Supply Chain & Freight as their fastest growing segment in Q3 earnings, growing 16.5% year-on-year, while US domestic grew "only" 13.8% with the note "continued elevated residential demand". SC&F is not solely domestic 3PL, so it's hard to be sure how that sub-segment is doing, but it's probably also under volume pressure.)

[dfox]

They do support scheduled shipments for a few customers who pay significant premium for that. What they cannot reasonably do is to do internal buffer for their own internal shipping capacity because the whole system simply is not designed for that. There is some somewhat significant and usually unnecessarily large capacity (because it is optimized for through-put, not storage efficieny) for warehousing of in-transit packages, but the current demand is so large that warehousing capacity is the limiting factor.

[donor20]

The key issue is that currently, any warehoused shipments will INCREASE ultimate required throughput rather than decrease it, because most holiday shipments need to arrive before 12/25, and the curve of shipments is increasing not decreasing.

So if you had some buffer, you'd be buffering into more constrained capacity rather than less. Buffering works better if you buffer into a quieter period. That's not this sitution. So yeah, backpressure needs to flow to shippers in terms of pricing etc.