If servos never failed in flight or batteries did not drop a cell or engines never shutoff in flight as well I would believe this but fact is things do happen beyond what you could possibly check. Yes proper checking of batteries can help you see a problem with a cell but if a solder joint comes apart on a tab and the battery was isolated from vibrations, and the tab was covered in heat shrink then how are you going to tell? I've had one engine crack the crankcase in flight resulting in a dead stick, ended up replacing the crankcase because of a defect in material. Again not able to forsee this. These planes were not lost

How about covering lifting in flight because the balsa below it separated (some staying glued to the wing ribs and some staying attached to the covering) on a certain ARF. This Yak was known for this on the first production run and many were lost. In my case I did a video review of the plane and with date/time on the tape. 2 hours after the ironing I flew the maiden and the covering on the left wing lifted, letting air inside the wing thus destroying the wing internal structure. this one I did crash, had no choice as it was heading towards the pits and I was losing control to the point I could no longer keep it going in one direction.

I'm not trying to be a pain, I am showing that you can have problems beyond what you can possibly do to prevent them. Yes they were manufacturing defects but nothing the pilot could have done to forsee them so not every crash is pilot error. I would love to hear what caused your off field landings and gear removals.