Yep. While FedEx doesn't deliver on the weekends either I believe it keeps cargo moving.

The Shipbikes site explains up front that you should leave at least one extra day in case of a delay. I always leave several days. For my recent trip I was arriving on a Saturday. I timed it so the bike was scheduled to arrive at the Missoula REI on Tuesday.

In all fairness, airlines can lose luggage. When I did the 2002 Cycle Oregon five of us were waiting for bike boxes at the oversized luggage pickup area of the Boise airport. Only four bike boxes were brought out. The disappointment on the face of the fifth person was palpable. Fortunately, there was an early flight the next morning. The guy's bike arrived in time for him to catch the bus to Nyssa, OR, where the ride started.