No. If you can’t multiply in your head, you are crippled in any quantitative reasoning. You have interjected too many steps in estimating, calculating, judging, etc.
This is not to say there aren’t useful, non-quantitative pursuits.
This is not to say there aren’t useful, non-quantitative pursuits.
Incase this is what you mean: remembering the multiplication table is the antithesis of multiplying in ones head.
But it's not! Because in order to be able to multiply numbers in your head efficiently you must remember the multiplication table.
Additionally my experience tells me otherwise.