Well, that's probably because you are understanding it wrong. The first, quick, poses are made for you to warm up, loosen your arm, and grasp the movement and feeling, instead of having a perfect drawing; these are gesture drawings (
http://www.sophia.org/tutorials/introduction-to-gesture-drawing). Then the Class goes into longer poses for which you are already prepared and able to grasp the feeling and then be able to capture the likeness. Try imagining athletes: they stretch and warm up and only then run a marathon. The Class automatically makes that "schedule" for you, while Standart gives you freedom to personalize your schedule. Another difference is that Class mode is like a live drawing class/session, which is also great if you have the time to spare.
I like using both tools; I don't often have time to make classes, so I just go on short 30 seconds poses, and once a week or so I make a 30 min class (not always complete -oops). I recommend doing so as well. A tip for short poses (up to 2 min) is really not focusing in anatomy at first, just settle what speaks to you the most in the pose, and then refine; also don't rush. Keep calm. I also recommend doing them traditional instead of digital, it's easier.
Useful tutorials I've found are:
http://design.tutsplus.com/tutorials/how-to-draw-a-stick-figure-a-complex-guide--cms-23620 and
http://design.tutsplus.com/articles/human-anatomy-fundamentals-learning-to-see-and-draw-energy--vector-17027 ; they are worth checking out.
Summing it up, because this kinda seems like a rant for me, I think this is the best order:
-get used to gesture drawings: 30 second poses on standart
-start applying anatomy: 1-2 min on standart
-get detailed: 5 min on standart (refine anatomy and add bits of shading)
-get more detailed: 10 min on standart (y'know shading and stuff)
-apply all you trained: 30 min on class
Hope I helped!
