At the previous airline I worked at, on line up WX radar on; exit active WXR off. Interestingly even at an airline which had moved onto multiscan weather radar, there were many pilots who didn't understand it / didn't know how to use it, therefore didn't trust it. We also used to test the weather radar as part of the pre-flight scan (med based airline).
At the airline I work for now, we switch the radar on and off as necessary. I still meet captains who think that the reflected beam off another aircraft will be enough to fry your nuts - power output has gone down so much on modern units that you could theoretically quite safely (as far as we are told) stand more than a few feet away from the business end of the WX radar while it is on. I suspect WX radar is a poorly understood area for many pilots - myself included, although at least I read the manual.
I know a crew who using my latest airlines cultural approach to WX radar flew into a CB while not monitoring things outside of the window; but monitoring EFIS without WXR on...