Repeating intermediate timer events will only fire if the attached process completes successfully.

public Void call() throws Exception {
    this.trigger.nextFireTime(); // need to pop
    if ( handle.isCancel() ) {
        return null;
    }
    this.job.execute( this.ctx );
    if ( handle.isCancel() ) {
        return null;
    }

    // our triggers allow for flexible rescheduling
    Date date = this.trigger.hasNextFireTime();
    if ( date != null ) {
        scheduler.internalSchedule( this );
    }

    return null;
}