It would be very handy to be able to chain triggers for events where waves are timed but there is no textual trigger between waves (Pellucid Grotto raid in Underfoot, for instance).
It would be lovely to be able to have the wave1 timer trigger the wave2 timer when it finishes, but short of manually chatting something to myself, I haven't found a way to do this.
Edge case? You could easily argue that, but it also shouldn't be a huge amount of development effort to implement (add a UI element similar to the end early listbox for 'trigger after' or something like that, then a trigger picker for the front end, fire off the trigger's event on the back end in the timer complete handler).