[EricH]

To quote Billfred from some time ago,
"At the same time, not having particularly scarce COTS parts you put on the robot would be a bad call as well. Kit wheel? Someone probably has them. N-tooth IFI sprocket? You might get lucky. Part Made By A Local Company When You're Competing 800 Miles Away? Bring three."

If you have a given part that is that critical, you should have spares if you might need them--or if you probably won't, due to Murphy's Law.