Mark: If you have the bessa r and begin taking a picture with the cap still on the lens you're going to get some really weird meter readings. That should alert you.
With a rangefinder camera, the moment I pick it up I remove the lens cap and stick it in my pocket, where it remains until I am home for the night. Otherwise, if you take a few shots, then replace the cap, put the camera in the car and start for home and see something that's suddenly right there and won't be 'right there' much longer, you stop, leap out of the car and OOPS - take two shots before you realize the cap is on the lens.
My rule: Take cap off in morning when you get up, put cap on at night when you
go to bed..
Hope this relieves your anxiety.
Ted