If the sampson stretch is held for the 30sec per leg that's one minute per stretch. Multiplied by 10-15 reps is 10-15 minutes times 3 sets is 30 to 45 minutes just for the stretch. Plus OH squats, sit ups, pull ups, dips and back extensions.
I realize the benefit of a warmup but I think and hour+ warm up is a little bit much.
Of course, there is a good possibility that I don't know what I'm talking about or I'm over analyzing to avoid actually doing a WOD.