Yoo your short gestures are unreal levels of good, I fell some of your shorter gestures are better than the longer ones XD great job. I also like the idea of painting them in, it makes seeing their silhouette much easier and also to see negative spaces - I might just give this a try myself
As for the faces, the last one in the left has an ear too high and there are a couple of chins that are not parallel in perspective to the brow line, but apart from a couple of those details I think they look very convincing. I would consider using even fewer lines in some of them, less is more
Cheers and keep up the great work!