I've never lost anything from a safe nor have I ever left anything in a safe.
After years of travel I have a set method for arriving and leaving a hotel room. My wife used to think it strange but experience wins out.
I always knock the first time I enter a hotel room; you never know. I've never found someone in the room but I did enter an occupied room once so the potential is there. The desk assigned the wrong room.
Here's how to leave a hotel room and never forget something. Pack and stage everything just outside the door. Go back in search the room. Don't look around, search it. I open every drawer and run my hand along the bottom into all four corners; same with the safe. Look under the bed and behind any furniture. Turn over the bed linen. Did you bring a pillow? Check behind doors for stuff on hooks. Check the shower. Pick up the towels and put them in the tub / shower; underwear likes to hide here. Stand on something to check any shelves (or the safe) that's above eye level.
It takes less than a minute. Your spouse and children will stop rolling their eyes when you come back out with a bathrobe, keys, video game, etc.