You should definitely do a spin down calibration. There should be something in the Elite app on your phone. As @Brennus mentioned, a spin down at the start of the ride vs one say at the end of the ride will yield diff results. Most manufacturers will recommend 10-15min of riding before doing a spin down. When I owned a Kickr1, I would do a spin down at the end of a ride. Then, it would be good for over a month (regulary compared it w/my bike PM). So, I would do a spin down every 3-4 wks at the end of a workout to maintain things. My trainer and bike were stationary. If I were always setting up and packing up the trainer, this would not have worked.
As for the L-only, here is something from a while back for you: