The opposite of this is a very non-standard prescription like mine. Mine is so unusual that neither my own optometrist nor any of the lens outlets in my city have the blanks and even the custom houses have to special order for them. I doubt any Japanese local shop could produce them very quickly, either. For that reason, I always carry a spare pair and on at least one occasion had to use the spares when my first pair took a dive on the shinkansen.

You need to plan ahead. If you have simple or very common lens requirements, you can probably get replacements in less than an hour. But otherwise, probably not.