To each his or her own. After catching a nasty foot fungus my first night out on my second Camino, 2014, at Orisson, I figured out why my feet smelled like cheese even after washing thoroughly with soap and water. it took a couple of days for the odor to get truly heinous...
The pharmacist at Pamplona was VERY amused when I showed him my Google Translation of my description of the problem. Whereupon, he just reached over, next to the register and handed me a tube of anti-fungal ointment. He commented (in English) that "everyone has this problem sooner or later..." We both had a good chuckle over the dialog.
The fungus was gone three days later. But, lesson learned. While at Pamplona, I found a China Bazaar and obtained an inexpensive pair of flip flips to wear in the shower. I got three Caminos out of those shower sandals, and did not have another foot infection problem. I bought the cheapest sort that fit my feet comfortably.
Now, my standard footwear kit consists of: Keen Targhee II mid height boots for walking all day, Ecco casual sandals for aprés walking and off-day use, and a pair of rubber flip-flops for shower use. The latter are NEVER worn outside the room I am staying in, or in an albergue, in the space from bunk to bathroom, shower, etc.
I could cut a couple of ounces by adopting one pair of waterproof "shoes" like Crocs for both casual and shower use. But THAT risks bringing in Lord knows what from having walked outside. So, out of consideration for all, I opt to carry the slightly extra weight necessitated by the three footwear items.
One confession, I do admit to upgrading my worn out flip-flops to a far more comfortable pair of Oofos. Occasionally, I will wear them outside. When I do they are carefully scrubbed with soap and water in a sink, before being brought into the shower again. Yes, I can be slightly OCD when needed.
I hope this helps.