There's a Note just above the instructions for running timersession:
It tells people to edit domain.xml, which is not something we normally advise – they ought to use the admin console.
It also tells them to change an element that doesn't seem to be in domain.xml any more, even. By default, all you see is
After I changed the default with the admin console, the following appears:
This indicates that minimum-delivery-interval-in-millis is an attribute of ejb-timer-service, not an element. I don't know how long this has been the case.
The note should be corrected.