It will be common to change classes which contains @Schedule timer methods.

In case such methods are removed or renamed (for persistent calendar timers) the server will log the following warning forever for each invocation.
WARN [org.jboss.as.ejb3.timer] (EJB default - 1) WFLYEJB0161: Failed to reinstate timer 'ejb31-timer.ejb31-timer.SimpleScheduleSingletonTimerBean' (id=1a419372-d807-43d8-ac77-5be6696b022d) from its persistent state

As this is intentional there should be a WARN message at (first) deployment time and the timer should be removed from the persistence.