I've never weighed my soaps but dividing the net weight by my number of shaves, I'm somewhere in the 1-2 gram range on most soaps. With creams, probably more in the 4-5 gram range.
It helps me to estimate how long i can expect a soap to last and look forward to it ending and a new one starting - ideal for when the climate changes and i want to move to my wintery soaps for example.I don’t bother. I just load my brush and lather my face. It doesn’t worry me how much soap or cream that I use as I have enough to last me quite a long time. For the members that do weigh everything, hats off to you for going the extra yards. It always marvels me how our brains think. How we can look at something and get two different opinions, and how something that means nothing to me can stir someone to go that little bit further.
And lastly an ad boasting 350 shaves from a stick (so apparently an ancestor of @AimlessWanderer has been giving his figures to Colgate in the 1920s).