Allow Schedule Updates? controls whether attendees can change their own talk schedule after they have completed registration.
Leave this on if attendees should be able to add more talks later from their attendee schedule or from talk pages. Turn it off if you want their post-registration schedule to stay fixed, which can help when you need more predictable session numbers for planning.
To change this setting, go to Event Setup > Registration & Checkout. Under Can Attendees Build Their Own Schedule?, switch Allow Schedule Updates? off.
When this is switched off, attendees will not see the self-service options to add or manage talks after registration. They can still access the talks included with their ticket, and event team members can still manage attendee records from the dashboard.
This setting is separate from the initial checkout schedule step. If you want attendees to choose talks during checkout, keep Can Attendees Build Their Own Schedule? configured for that flow, then use Allow Schedule Updates? to decide whether they can change those choices later.