In both the Visit Number Report and Days Before First Purchase Report, there are no bucket ranges possible. It's just a list of rows. Buckets allow you to consolidate data and get a much better view of trends. The only way is to export into Excel and then manipulate. There should be a way to set them in a custom fashion by range, number of them, and order/sort them by label arbitrarily.
The same would go for the Return Frequency Report. The preset buckets sometimes seem to obscure the picture (especially when they are out of order) for users that go beyond one month. Being able to change them would be much more helpful.