I agree; Saturday is the most reliable 2-day shipping day if you know that the box will get out of the PO and not spend the rest of the weekend at the loading bay door waiting for Monday to arrive. We're entering a tough time for shipping plants because of the high sun, hot temperatures and the fact that a lot of plants are in active growth right now. That's a combination for killing plants. Even though winter is tough too, I've received far fewer DOA plants in winter than in summer.
Double boxing - packing in a small box and packing that into a larger box - is a great way to protect against the weather, but Priority Mail's relatively new volumetric pricing makes double-boxing extremely expensive for anything but the smallest plants. Prices can easily jump from $5 to $25 as the package volume goes past 1728 cu. in. That's only 12x12x12. But even the extra $ is money well spent if it can protect a rare or valuable plant. There's no point in spending $5 to roast or freeze a plant. It costs much less to just put it in the oven or freezer at home and you save a trip to the PO. If the plant isn't worth the cost to safely ship it, don't make the trade.
Bruce in CT
Madness is something rare in individuals — but in groups, parties, peoples, ages it is the rule. Friedrich Nietzsche
Weight and distance can also affect the price of priority shipping. For instance if I ship a 2 lbs priority package standard size box from Los Angeles to San Francisco it is $4.95. If I ship the same package to Miami it is $8.70. If it was 1 lbs or less it would be $4.95 for either destination.
Flate-rate shipping is probably the way to go with heavier packages but then you are constrained to using the USPS boxes.
Postal Zone Charts
Grand Hotel... always the same. People come, people go. Nothing ever happens.