For me, any extra lather (which is usually enough to do one more bad pass) gets used to wash my entire face. Tbh, i might even use it on my hair if its prior to a shower.
I’m trying to find a way to use more soap up rather than less, and I think bowl lathers tend to generate more lather and use more soap than face latherers, but thats all anecdotal and not supported by any real research. I cant imagine that the last remnants of lather, especially voluminous, has a lot of soap in it, but I guess over time, it could be a fair share of product, if you are aiming to be efficient.
I’m trying to find a way to use more soap up rather than less, and I think bowl lathers tend to generate more lather and use more soap than face latherers, but thats all anecdotal and not supported by any real research. I cant imagine that the last remnants of lather, especially voluminous, has a lot of soap in it, but I guess over time, it could be a fair share of product, if you are aiming to be efficient.