Would it not be a lousy user experience if a fan gave you their email address, downloaded your album, then returned to download another track or album that you also made email-required, only to have to enter their email address again? YES IT WOULD. That’s why once a fan (or conscientious band-member testing their site) provides an email address for a download, they never have to do it again (at least not from that same browser, for that same band, unless they clear their cookies). For this same reason, stats spelunkers may notice the number of downloads exceeding the number of email addresses collected.