I have been training on quickposes.com until its recent demise, and I really learned to appreciate same length sessions. Say 10, 20 or 30 minutes of quick sketches.
I don't like the time schedule you have on predefined lessons, so I started a "same length" sessions, and somehow naively assumed it would end after 20 or 30 minutes. I started drawing, then it turned into grinding and I kept thinking "This got to end sometimes, right?". I finally broke off, and counted 73 sketches I done. That's more than one hour of sketching, without any break, it get's really tiring after a while and at the end the quality started to visibly decline. And it seems for all that I don't even get the cheap endorphine kick of counting this time for practice time on my profile, as I had to break off the session manually.
I would really appreciate that one extra button for the Same Length sessions, that lets me chose after how long a time it automatically ends and counts the time spent towards practice time.
I just did some poking around; I can see your time was, in fact, recorded! However, what's being shown on your studio page is probably this message:
"Upgrade your account to track your practice time and ensure you're sticking to your goals."
Although the drawing tools themselves are free for everyone to use, we ask that members who want to use tools like tracking their daily drawing time support us starting from $1.49 a month. This helps us continue to be able to offer the basic drawing tools to the world for free. :)
As for your suggestion about adding a limit to the same-length sessions, I'll definitely look into that. I'll also mention that at out top support tier ($14.99/month) you can design your own class sessions of any length with any combination of pose lengths and breaks, so one of the things you could design would be 30 minutes with every pose set to 30 seconds. :)