For the most part, this is us... I don't really know what is normal to stock up on in other households, because my mom was the opposite. She is a hoarder and has hundreds of bottles of shampoo, for example. (Unopened, some expired, others not. And she keeps buying more.) She has several refrigerators and a three car garage packed full of food as her pantry, several fridges, etc. That's beyond the full kitchen and two dining rooms full of food.
I think I took a bit of an opposite approach to her because I tend to have only one of things. Well, maybe not one of everything, but definitely on the low side. Our baby gets swaddled every night, so we have three swaddles - one for that night, one for the next night, and one just in case she pees on it or something. We have one car. We have one wooden spoon. (I have a Rubbermaid tote in the garage for extra pans/pots/spoons, etc. So if I'm making Thanksgiving dinner and need a couple of extra pots to multitask, I'll be able to... or if I buy a wooden spoon and it comes in a set of three, I'll save the other two. But I just have that one "extras" bin and that's it. It's not in day to day use.)
I used to be into stocking the pantry but found I was always in stock-up mode, and then things spoiled or I just never used them. Now I make conscious efforts to NOT have a pantry... We do have a freezer but I'm trying to be really mindful of what's in it. I will sometimes buy a really good bargain of food item if I *know* we're going to use it up, but I'm starting to like the look of having less full shelves. Call me crazy, but we waste (and spend) much less as a result. Weird.
I figure, you are going to get about the same uses out of something whether it's the only thing or you have a bunch of them. If I have ten pairs of shoes, it will take ten times as long for me to wear them out than if I had one pair that I wore every day. So I don't really see a huge difference, but then again, I'm not really much into needing variety from that type of stuff. (Except in purses - I have a weakness for them!) So I have one pair of sandals, one pair of boots, one pair of snow boots, one pair of hiking boot, one normal pair of shoe, etc. But that's about it.) Yeah, sometimes it comes to bite me. Like the other day I woke up and wanted to wear my hiking boots, but remembered at the last minute that I had gone to the park the day before, gotten them muddy, and was distracted when I got home so I didn't clean them off. So I had to wear my winter boots, which wasn't SO terrible but it didn't really go with my outfit. Whatever, though. That was less stressful to me than having a closet full of second, third, etc. pairs.
For the most part I do like having one (or few) of things. But I don't want to commit myself to that 100%. It's more of a guideline than a rule.
ETA: Just the other day I did a laundry closet cull. It seemed like I was *always* washing towels, bedsheets, etc. for everyone. So I cut it down to one towel per person, one backup for each bathroom, and two guest towels I stashed in the guest room. Same with bed sheets, I kept two warm sheets and two summer sheets (and matching pillowcases) for each bed. Much more organized of a closet - and I've had MUCH less laundry to do now that people weren't chucking towels into the bin after every shower. It actually HALVED my laundry load. And electricity bill, etc. Now even if a towel gets worn out quicker, how much does it cost to replace a towel? (We don't do fancy ones, lol.)