Whenever any of my weapons are out of my immediate control and not in my hand (including - in a safe, gun case, vehicle, etc..), I drop the mag and check the chamber. This includes out shooting in the forest or the range with anyone who is along on the trip. I always treat every gun like it's loaded, but still check the weapon again if I come back from checking targets etc. I check them before I put them back in a case for transport and I check them again before I put them in the safe. Mostly because I know as every year tics by, relying on good fundamentals is more trustworthy than my memory.