On my planes w/o telemetry, I leave the Flight Data Log reader in for the first few flights to gauge how far out I can fly the thing. (e.g. I see a couple Frame Losses and I know I was near the edge of the transmitter's coverage area.) Every time the Rxer is powered off and back on, the data resets. Once I know how far out the plane is safe to fly, then I just put in the logger when a problem is IDed or suspected. To keep things as simple as possible, until a plane has several flights on it, I like to use the flight log reader. Then, after several flights, I put in telemetry.

On my planes with telemetry, the data is logged in the Txer. The Flight Log Data reads out on the Txer's screen. I get an alarm on a Frame Loss, etc.. I also have telemetry on my gas plane's RPM, Head Temps and Battery Voltage which reads out on the Txer. I put alarm set-points in for each parameter. In-flight RPM data is great for testing various props to get the engine in its powerband. In-flight head temps are great for testing different baffling arrangements to get the best cooling, etc. I love real-time telemetry. But, until the plane has a few close in flights under the belt, I avoid it just to keep things as simple as possible.