I called exactly at 5AM PST today and they answered immediately and was done in a couple of minutes. Probably the wait times is like the wait times in any store -- randomness due to variations in demand (today's Go For Broke was the most boring issue of 2021), environmental (such as being middle of the week after Memorial Day), USPS staffing levels (maybe more people are on the phones mid-week, intentional staffing, variations due to day of week).
I'd expect commercial online stores to use real time inventory management software, but not .gov.
I see that there are Tap Dance imperf ( no die cuts) panes on the market. The USPS never listed these on their web site nor did Linns have a USPS item number available like they did for the other no die cut press sheets. How is the average collector suppose to ever get these issues without buying at a very high markup on the secondary market ? The USPS needs to get their act together.
For the Tap Dance issue, I called the USPS a few days before the 7/10 Saturday release about availability. Also, had to ask about other future releases before the catalog was released.
It's really annoying the quarterly USPS philatelic catalog is released too late for "new issues". They seemingly take around 2 weeks after the quarter starts so anything released during that time is it to us to figure out.