Whilst i dont travel with anything valuable except passport, credit cards, phone, tablet and sometimes a waterproof camera, i do sometimes use safes and I've never left anything behind in one.
I always empty it and put everything into carry-on bags the night before departure; and double check again in the morning.
IME it is not always feasible to have your passport or tablet or all cards/cash on your person all the time, especially if like me you often do very active or water based activities such as diving/snorkeling, sea kayaking, canyoning, ziplining or visiting sites that dont allow you to bring any sort of small bag inside.
I also always keep a spare credit and debit card stored separately from the ones on me as back-ups in case of loss/theft (plus versions on my phone), usually hidden in inside pocket of a jacket or bag locked inside a carry-on case or larger case in my room.
My main rules are:
1. If you cant afford travel insurance you cant afford to travel. And if you haven't declared an activity/location on said policy dont do that activity or do a side visit to that place on a whim.
2. Always leave a copy of your full itinerary and contact details with a non-travelling trusted family member or friend including details of your travel insurance.
3. Never knowingly book a hotel room or air bnb that has a shower/tub combo; never accept an upgrade to a room without a walk in shower.
4. Eat local, McDonalds and its ilk are only acceptable if you are stuck in an airport without lounge access and there are no other options.
5. Use bottled water to clean your teeth unless you are 100% sure the tap water is safe.