It really depends where your traffic is coming from. When I was doing organic, we’d have months with $100k profit split with my partner, and then months with $0 because you can’t predict virality.
Paid ads (meta/facebook specifically) have been way more consistent for me and everyone I know once you have a winning product. You can usually predict your income pretty well once the campaign is working, but ads don’t last forever, so you still have to keep testing. Stores can go to zero fast, but you can also keep one running for years or turn it into a real brand.