Your belt rig sounds like something I would use for a "bump in the night", or "something is spooking the cows".
Having the necessities organized ahead of time cuts down on confusion, especially if you just woke from a sound sleep.
As far as a "bug out" kit, here are some of my thoughts:
Likelyhood of a Red Dawn scenereo is somewhere near 0%, so I won't think along those lines.
What will likely cause me to have to abandon my home are things like -
1. FIRE (caps intended). This is far away the most likely threat everyone reading this is likely to face. 2 of my next door neighbors had their homes burn to the foundation, and 4 more good friends had house fires that rendered the homes uninhabitable.
So, for this reason, I keep a "go box" with all important documents (birth cert, marriage cert, passports, credit card, insurance papers, etc) stored where it can be quickly grabbed when the smoke det goes off.
Also, a complete set of keys for every lock and vehicle I own. These keys are also in the go box. One of my neighbors had every key they owned melt in their house fire. Locksmith bill was huge, and took more than a week to get to everything.
And next to the go box is a bag with 3 days of non pershable food and some water, along with a shirtm jeans, socks and underwear for everyone in the house.
2. The next threat would be from severe weather, mostly tornados. Plan would be to retreat to storm room with the go box, and go bag. Wait it out.
3. On down the list would be a chemical spill on the railroad less than 2 miles away. Would again grab go box and bag. Depending on where we would go, would also pack a hi-cap handgun.
4. Civil unrest would pose a challenge. Doubt anyone would be able to easily move about, so shelter in place, no bug-out.
5. Severe heat or cold no reason to bugout. The house is designed to be habitable without electricity. Has passive solar heating and cooling that works.