One of the reasons that I follow the 2 hour rule even when the first leg is domestic (OKC-ATL/DTW/MSP) is because here one never knows if the RJ (after the 6:30 am MD88) is going to be on time. Getting to the airport early gives some room to find another connection and even another international flight when there are problems with weather, mechanical, late crews, etc. The lack of a SC at OKC is a distraction but office work can still be done with an iPad.