It's always a good idea to preflight the aircraft before each flight. It only takes a second. Grab the propellor and see if you can shake the engine. If it moves, then tighten it. Check the control surfaces (gentle tug to check the hinges and a wiggle to check for play). Same thing for the wheels and gear. I do this religously and it's paid off on 2 occasions. The first time I saved my GP Decathalon from certain death. When checking my rudder in preparation for my second flight of the day I noticed that only 1 of the 4 CA hinges holding it on were still intact. The second time, I found that 2 of the 4 screws holding the right aileron servo on my 1/4 scale Fly Baby were gone. Just think of all the time and money you have invested in your model. It only takes 30-60 seconds to do a decent preflight on a model.