It is very tempting to see the soap sale after the holidays. At 50% off the regular price of bath soap, I could buy a ton. Seriously though, we probably bought a supply of soap for a year or 2. Soap has no expiration date therefore there is no worry for the bulk purchase. Storage is not a problem either. You can store it anywhere that is dry.
You are right it is a good idea to stock up on soap when it has a great discount. I have done this a few times where I buy soap for an entire year just because it was almost free. I actually try to stock up on anything that does not expire. Great values are always good to take advantage of.
Soap is already fairly cheap in my area so when there's a deal, each soap usually costs around 10 cents each or less. We also sometimes visit companies where they store or throw away slivers of left over clean soap and we can have them for free instead. You can also save some money by sticking a smaller unusable sliver on a new soap.
I have never bought a large supply of bathroom soap unless I have small business to cater to the grocery needs of my neighbors. My wife who does the shopping every weekend buys a two or three pieces of bath soap enough for a week to be consumed. Probably within this year 2017, she would be constraint not to buy soap for we have enough of it given to us by our friends and business office co-employees during the Christmas season. At least we can save money in buying soap supply for our family.
I recently ordered a stock of soap from overseas to last me a year. It is my favourite brand and I don't get it at my current location. The shipping was free for me so it was still economical. I usually stock up washing soaps as they usually are at a discount and I obviously need them on daily basis.
The thing which I've noticed is that, most of the brands of soaps are always in sale. However, soap is a pretty cheap product. Given that, I do not buy them in bulk as I like to keep on changing the brands. Piling up a stock would otherwise force me to use the same brand over and over again.
I think that I always get a little more excited when the deals are on the things that I have to buy. It just makes it that much more obvious that am making a good decision and saving some money.