The part that gets me is how a changing bag leak looks exactly like a camera leak, so your brain goes straight to the expensive thing first. There's actually a trick worth knowing: load a roll of cheap film, pull the leader out, and leave it sitting in the bag in direct sun for an hour before you ever run it through the camera. If the film fogs, the bag is the problem, and you just saved yourself a full tear down. Zippers fail in a way that is almost invisible too, since the pinhole is usually right where the pull sits and the fabric folds over it. Also worth checking the seams where the arm holes meet the body, because those rub thin way before the zipper does.

Ever had one of those jobs where the mud just eats everything you set? Same thing happened to me a couple years back on a drainage project, we were fighting soft ground all week and my old setup was useless. Boss finally dragged out the GPS gear and I was rolling my eyes hard, figured it was just fancy junk for the office guys. Fast forward two days and we're cutting grade faster than ever, no more hunting for control points that some idiot knocked over. That job made me a believer too, no sales pitch needed.