That's marvelous work, on any feet you've quickly sketched out, slvsh. Very great job on recording the gestures and movement.
If I could and should nitpick on them, then these feet are a bit too rigid and even with the foot relationships (perceptions of proportions and angles) Would you kindly be able to draw the largest and longest of lines with 30 minutes of 10 minute feet? (3 feet)
The basic reason why you could and should do this is as long as you loosen and liven up those feet drawings, then those would be able to be the loosest, free-est and most expressive with the foot action. Not to mention, their lines of action and rhythm.
Hope this helps.
I appreciate your criticism and suggestions, Polyvios.
I will try to improve the method of drawing lines, and the proportion and perspective is estimated to be in a long time I still have to solve the problem, I will continue to learn ~
I really admire your clean finish on the final sketches. That looks really professional.
On the short sketches, I would try to reduce the number of lines still a bit. You don't need to draw out every toe, to communicate the overall form or position of the foot. The four smaller toes can often be well represented by uniting them to a single geometric form, as they mostly move together anyways.
Finding some simple shortcuts for feet will be handy when you do full-body poses, and then the feet won't be the star of the show anyway, but just the detail, that you don't want to distract from the main event.
On the other hand it might be a good idea to draw out the calf a touch longer on the quickies, so you are more aware of the relation between foot and leg.
Not much to critique here other than personal artstyle choice- bc these are 10/10