Is this the right scree slope?

The route from Avalanche Peak to the Crow valley follows the Mt Rolleston ridge to the north for a while. Only when the ridge starts to ascend seriously, the route leaves the ridge and descends a long scree slope west, all the way down to the valley floor. Great scree running, if you get it right :). And that's just it, it is crucial to get the right scree slope. If you take one too early, you'll either fall to your death, or, preferably, notice in time that it gets too steep and decide to slog back up the scree, which would be very tiresome of course. There a several pointers helping you find the point where to leave the ridge. Quoting the DOC route description: "You can see the full length of the scree, from the ridge to the Crow valley." Well, from here we can see the Crow valley, and if you look closely, even Crow Hut. However, the scree doesn't go all the way down to the valley. That fact alone means that it must be the wrong slope.