Let's say that you have a repeated task and complete it - it goes to the Completed list. Once in a while you can go to the Completed list and delete tasks which are there.

Currently, you are presented with a question if the repeated tasks should be kept repeating. However, this question doesn't make sense for repeated task which have been completed as there is still at least one uncompleted occurence in the list of Incompleted tasks.

I suggest to remove this unnecessary question.

It can only be used if I delete a repeated task for which there are no more uncompleted occurences. Then (and only in the Trash list) user can be asked for a deleting of the repeated task.

Rationale: once the task is completed, it is no more "repeated series" but "single instance of repeated task". So, no completed task should have the "repeated" flag or this attribute should not be taken into account when the task is being deleted from the Completed list.