It really depends what you upload. The trick is to figure out what the buyers want. I've seen people with multiple downloads per file and small portfolios. Then there's the wanna bees like me, trying to find the right niche. I did hit a good market when I photographed the presidential candidates in 2016, but I'm looking for something new.
Try to develop icon sets that are unique, but still satisfy customer desires. Pay attention to what sells, your work and others work. Don't copy others, but learn from what they do and apply it to your own ideas.
I really think a bit of time spent in studying the market pays off in sales in the long run.