[topaz0]

Looking around it seems estimates vary by a fair bit, and the one you cite is on the high end. Other estimates are in the low hundreds, which is a very attainable number of reuses. But it does seem my memory was unrealistically low. Also an aspect that is not considered in these studies is that canvas bags generally carry more stuff per bag than single use plastic ones, so taking 2 canvas bags to the grocery store can save 6 or 8 plastic bags.

[TylerE]

The difference seems to be how far down the rabbithole you go - are you only tracking the energy to make/ship/(hopefully recycle) the bag or, as the study I linked does, goes all the way back to the plant in the field. Cotton is very water intensive.