My nurses suggested that I stay on the big (night) bag. They advise that the bags are intended as single use, and to clean then to the point required to change and reuse them was not practical for me to handle in the shape I was in. The insurance only allowed two big bags, one leg bag.
The nurse reminded me that the doctor, who said "sure, no problem", was not going to be there at the ER at 3 am when I showed up in screaming pain because of a uti from a less than clean bag change.
I stayed on the big bag. Before the cath was out, walking any distance was torture anyway, so the walks were brief.