Badges, screens and banners
Codes on screens and banners are scanned from further away than you expect. Size them for the back of the room, and leave them up for at least half a minute: people need time to take out a phone.
Badges are small, so keep the link short. An editable code always encodes a short link, which keeps the pattern simple and easy to read even at 2 cm.
Change the plan, not the print
With an editable code, the printed badge can open the registration page before the event, the live schedule during it and the slides or recordings afterwards. You change the link; nobody reprints anything.
Link options can also start and stop a code on given dates or after a number of scans, which suits early-bird offers and limited sign-ups.
Measure attendance and interest
Scan stats show when people scanned and from which city and device. A separate code per session, stand or poster tells you which ones drew a crowd.