See IOF
Control Descriptions; scroll to page 16 for pictorial examples of different terrain features. NB A 'gully' in most countries other than Oz is known as a reentrant.
In orienteering, a gully can be as small as a kink in a single contour, or a deep ravine with many contours.
I agree with you that some of them could have been placed on nearby features, but they were all legitimate H course sites.