It is also worth noting that mitochondrial eve can change over time. Say this person had 2 daughters and at some point it just so happens that all of those descended from daughter 2 die out. Then daughter 1 now becomes mitochondrial eve, since that is now the most recent common ancestor.

Obviously our math isn't getting us precise enough to detect that single generational change. But recognizing mitochondrial eve is a concept (whoever the current most recent common female ancestor is) rather than a person (that gal named Ugh Ugh who lived in that cave over there) is helpful. It is pointing at an individual at a time, but that individual can change as human populations change and matrilineal lines die out.