I've had problems with FedEx. I paid extra for Saturday delivery so I'd be home to accept some fish. The fish left the seller Friday evening as scheduled, but then Saturday came and went. It was late autumn and cold.
Fed Ex said the box was "delayed" at their main hub in Memphis and all offices were closed on Sunday so the fish wouldn't arrive until Sometime Monday. By that point they would have been in the box, in a cold warehouse for 3 days with heat packs that would last only 24 hours.
The fish eventually arrived Monday and all were alive when they got here, but clearly stressed. I acclimated them gently, but slowly over the course of a few days 3 out of the 5 died. Very sad.