I would not leave it in a lock mode unless necessary. The main reason I would like to leave it in 4wd lock (Sand Mode) is when I am driving on the beach. Over the years my main off roading is beach driving often in some very soft, deep sand and it doesn't take much to get stuck. The few times I drove the Renegade on the beach this year it did great but 1 time the front left started to sink pretty fast and it felt like I was going to get stuck. I had been in Sand Mode prior to this and once I shut the engine off to fish a little I had forgotten to put the Sand Mode back on. It probably would have been ok with auto 4wd but the 4wd lock gives me a little piece of mind in these conditions. This is the first 4wd I have owned that resets back to 2wd when you shut the engine off. However I did have a Ford Escape with the auto 4wd feature and did get stuck a couple of times with it driving on the beach.