I've been seeing that some people change their bags, but am assuming that they are keeping their wafer in place. What is the benefit of changing the bag and how often would you do so? I find that I'm typically only changing the bag at the same time as the wafer because I can get a good 3-4 days wear out of the wafer and chuck the bag out with it as well. I've never had any problems with odour or issues with the bag, so was curious as to why someone would change the bag more often.

Some people use closed bags, so they would need to change every time they fill.
I know some who use drainables that change every day because in thier cases, they have an odor.
I wear a two piece, and will change out both the wafer and the bag at the same time.