Spring training in Phoenix resulted in huge crowds and sky high rental car prices.
Enterprise and its competitors were overwhelmed. The staff did it's best to keep up. I used my loyalty card to get to the rental desk without a line, but then still had to wait 10-15 minutes when I went downstairs where the cars are for an agent to show me a car and get the final signatures.
My standard for top-flight Enterprise service is Atlanta/Hartsfield. If ATL is 5 stars, Phoenix is four.
Note: All the companies share one facility and use a common shuttle bus. The rental car return was easy to find. There were loads of signs once you got near the place.