I've always played (and taught) the 'free index' fingering, particularly as it helps the beginner to learn to separate the fingers, and strengthens the little finger.

It isn't the most natural way to finger it, although it is logically the best - except in some circumstances.

Beginners need to be given 'hard and fast' rules to stick to - they can always experiment for themselves when reasonably proficient. It's good discipline, and weeds out the ones who haven't really got their heart in it...