Risk in this context is how likely the part will go out of stock or "end of life"-ed. If a part has no alternatives it is even more risky! When I designed a la

Risk in this context is how likely the part will go out of stock or "end of life"-ed. If a part has no alternatives it is even more risky! When I designed a large board oftentimes several of the tiny parts such as capacitors or resistors would go out of stock but this generally is not a problem if you are using a common part. If you have a good contract manufacturer you can flag any parts like these as "use equivalent OK" and they will automatically pick a new part for you if necessary, with the same or better ratings. Some companies also use their own internal part numbers for each electronic component (like a 10k 0805 resistor will be part AB1235) so then they can map that AB1235 part number to a list of acceptable manufacturer part numbers. That seems like too much work for me though!