Any particular reason for this tendency not to use DME, which was always available to us, and to my mind, is a hell of a lot easier to fly accurately.
Of course it's easier to fly a DME hold than a timed hold. Maybe the particular holds you flew we're published timed holds not DME holds?
If you can fly a decent timed hold you can fly a DME hold. If the hold was unpublished around a beacon for training purposes only, the FI probably wanted you to demonstrate you could correct for timing. Most NDB holds I've flown have been timed. There are of course both in the real world. That's what there training you for.