I think it would be a neat feature if we were able to delete all review data from before a certain date. I got sent some decks that had been used years ago by someone else and didn’t delete the review data before beginning. For some reason, all intervals are default, but the previous reviews still show up when looking at my statistics.
Unfortunately, I only realized this after I had already studied a good chunk of these cards, which is why I can’t just delete the review data now (as I would of course lose my own progress). Alternatively, a setting could be added to the statistics where all card data before a certain date is ignored. However, deleting the card data would be more useful, as there could hypothetically be a situation where you get sent a deck that was studied after you started using Anki.
This is probably not very important for many people, so I’d give it a low priority. Still, it might not be that much effort to code.
Thank you and kind regards