I have always added a few of this and a few of that on ever order when building and now doing maintenance as well. Shipping cost from Vans and Spruce are very high (spoiled by amazon prime) so adding some hardware seemed like a good idea. I hated waiting a week to get one bolt I was missing. I now have a great collection of most stuff.
Other tips is I bought and planned a big enough hardware container/system early on that allowed me to “fill in” sizes and grips. I did this because I took everything out of the hardware bags when I got my kits and organized them into the little hardware drawers.
I guess this really does not help the OP question but may help others still ordering and building.
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