I think using a cotton bag 173 times to beat plastic bags and a mug 1,000 times to beat disposable cups sounds completely reasonable.
Can you use the cotton bag 173 times? Cotton wears out over time. They also didn't ask about the cost of washing the cotton bag, which really should be done once in a while since they collect dirt and food particles - this will increase the times you need to use the bag. (it isn't clear if it lasts longer with or without washing - dirt is often sharp enough to wear the bag, but washing also puts wear on them) Similar…
> Can you use the cotton bag 173 times?
I can confirm: Easily. While I don't like the feel as much (the scrunching plastic sound is awful compared to natural fibers), PET bottles that are recycled to make reusable bags are incredibly tough. I had one that I used for 15 years(!) for multiple shops per week.