Close, but the five minutes, when I was a butchers boy in the dim and distant past, would have been 15 to 20, or I'd get sent back to do it again. Funny though, once I hit 16 and got my first motorcycle, I never had any trouble undoing tight nuts and bolts. Block scrubbing is a wonderful preparation for wielding spanners.
I seem to remember I was pretty good at press-ups too.
Our block was never washed, whatever went on it was covered with sawdust and scrubbed off. Only the final wipe down was done with a bit of muslin (that lamb used to come wrapped in, all the way from New Zealand) soaked in boiling water and well wrung out, to remove all traces of sawdust.