I have tons and tons and tons of hardware that I don't need, but that I got free or cheap.
I never have the specific hardware on hand when I need it, and that hardware is not sold in typical hardware stores like Ace, Tractor Supply, or big box.
Usually I'm looking for metric flange bolts and prevailing torque all metal flange nuts, with a corrosion protection coating that doesn't cause fastener embrittlement, in property classes 10.9 or 12.9.
Big box will have 8.8 and 9.8, without flanges.
Ace will have 10.9, but only in black oxide or phosphate and oil.
Tractor Supply will have lots of nylon locknuts, but not all metal deformed thread prevailing torque locknuts.
When in a pinch without the leisure of ordering from McMaster-Carr or MSC ahead of time, the highest quality hardware available locally can be found at a the parts department of a new car dealership.
I have literally looked at parts explosion diagrams of random truck chassis parts just to get the fastener size used to by the OEM, and from there have obtained the OEM part number to that fastener, and then called the dealership to ask if they had that part number on hand.
One time, a part counterperson quipped "you know, we are not a hardware store."
I responded, that may be, but you have the best hardware I can find locally.
I have 50 trays of hardware that I will never use, that I can't throw away because one day what if. And sometimes I do find something of use that saves a trip to the store and some money to boot. But I'm not sure that getting a general selection of hardware is as useful as having the optimal hardware for the specific use needed.