Critique Please

I've been drawing on and off for a while, but my goal for now is to accelerate my drawing speed. I feel like I spend too much time sketching, and I would like to reduce this amount of time.
Please see my drawing and if you could I'd like to have one tip on how I could improve it, or what feels wrong, and also one thing that you think was well done. Critique is very important, but I also think that highlighting what was great will also help me in keeping that habit. Thank you![img]https://imgur.com/a/OF1corJ[/img]
https://imgur.com/a/OF1corJ

The girl on the roof looks ace, and I like your overall style. For the girl standing in the foreground, her entire posture is derived from a single straight line, which you then tried to partition into right sized chunks (and you nailed the sizes only 70-ish %). It would look better, if you were more aware of indidiviual pieces: where is the chest, where is the hip, how are chest, hip and head connected by the spine, how do the shoulders sit on top of the chest. chest can be abstracted into a flattened half-egg, and seen from the side, it is almost never straight vertical, but slightly diagonal, so the spine ends up in a double-s curve. head in centre, shoulders slightly behind head, belly slightly in front on head, hipps in the centre again, but slightly tilted forward.