There is a particular spice mix we use to season our taco meat (or vegan equivalent). We need two packs to have enough of it for single serving. So it makes sense to buy the triple back that it's also available in addition to buying singles.
Obviously there is 2/3 of the time a pack or two left over. It's also a thing that I usually forgot to check before leaving to the store. I might have a vague memory that there were some in the pantry. But was it one or two packs? Better buy another triple pack to be sure there is enough of it.
Of course with multiple packs stacking in the pantry the problem just multiplies. For example if there were two packs left and I bought another bundle. The previous bundle will be all used. Next time going to the store I might remember that last time it was the last pack forgetting there was another new one unnecessary purchased then. So better buy another one one just to be sure.
Last time I didn't buy any. I was pretty sure there was still enough left at home. I was not wrong: back at home I checked, and found 7 packs of the spice mix!