I find ETE to not be useful for running (trail running) because it makes estimation based on the average pace. When running the pace is often inconsistent. It may slow down significantly because of tiredness. Or it could be faster towards the end if the first part of the run was uphill and the second one is all downhill. ETE doesn't take any of that into account.
It would be better if ETE or estimated total duration that OP is asking about was based on the last 30 minutes.
