They've had 5 launches for the iPhone and 2 for the iPad. No offense, but if you weren't aware of the strain, then you weren't tuned into any media or reports on sites like this or general tech sites. Apple's own systems couldn't handle the activation strain, and then when they could, specific carrier systems failed to activate correctly. In some cases it left activations in limbo states requiring multiple calls to get sorted. Hell, even last year's iPhone 4S launch had UPS straining. My regular UPS guy walked up my driveway at 7pm in the evening. He said they added staff in many areas to handle the load and were still having to expand their work hours. By his comments it was the extra bulk of it being a signature required package with that many units that caused the pain.
The partner advantage issue doesn't factor into it. With these products, all launch inventories will sell. Therefore, if they gave Walmart 100,000 and Best Buy 80,000, etc. (making those numbers up, obviously), all will sell regardless of which chains branches start receiving them earlier in the week than other branches.
I'll have my new iPad on Friday as well. The unknown is around activations, particularly on the 4G models.