After digging around, I found out that the number of items sold per day at a regular H&M store can vary greatly. Factors such as the store's location, day of the week, season, and promotional activities can significantly influence sales. On average though, estimates suggest a single H&M store can sell anywhere from 500 to 3000 pieces a day. However, it's crucial to remember that this range can fluctuate based on the aforementioned variables. So, if you're planning to shop, avoid peak hours to have a more relaxed experience!