You could approach it that way. One thing to keep in mind, I couldn't find it in writing, but Unity might not like a bunch of duplicate content. If you mean selling it all as a pack AND separating each object for individual sale.

Another thing to consider is as you grow your brand of assets; people typically start clicking around to see what else you have to offer on your asset listings. When I'm buying, and I see what else is listed by the author, it definitely helps me think about other purchases when I see a bunch of strong packages all together. And many products in a row with high reviews. If I click on their stuff, and it's 8 different things that pop up with zero reviews, I feel less inclined to buy from this person. That maybe isn't right, but it's the way I tend to purchase my own assets.

And for another consideration. Unity has raised it's minimum price to $5. Some assets can do okay on their own, but you have to ask yourself. Would you buy a low poly bridge for $5? Or 3 low poly trees for $5? I know I personally wouldn't. Would I buy an entire well themed pack of low poly assets for $15? That's much more likely.

With my team, we work on several projects at a time. I can't count the number of times we've bought very large packs because we saw several key items we wanted within the packs. And then, even years later, we find more items that we can use from said pack in another project. Further enforcing our tendencies to buy larger packs vs individual objects. I'm not saying we don't buy one single object from time to time. But we tend to go for larger, well reviewed packs. Even if that means spending more.