This is partially correct/incorrect. Open loop (uses maps and minimal sensors for fueling) is used at cold start and under any "hard" acceleration (several factors met in ecu). Closed loop is alway on once engine is warm (uses oxygen sensors, etc for fueling). This quote is from a thread on the outback forums to be a little more specific:
Fueling on these cars starts with the ECM knowing where TDC is. Then it relies on the cam position to manage injector timing. The injector pulse is determined by TDC, Cam position and the AF sensor feedback at any rpm. The cam sensor is affective from start up.
Higher RPM utilizes the AVCS system to help the car breath better and in conjunction the spark and fuel injector timing is altered based on feedback from several sensors listed below.
CKP
CMP
MAF
IAT
MAP
ECT
AF Sensor(s)
Rear O2 Sensor(s)
Knock Sensor(s)