So is Ashtanga yoga: There are several series. One learns one asana after the other. If an asana is 'mastered' the next asana is taught. This can last years sometimes, up to 5 years or longer.
Some yoginis get grumpy. They see that later in the series are asanas that they are able to do. They want to progress.
During the last 10 years asanas were introduced to me that I didn't like at all (garbha pindasana). There were other asanas I thought I'd never be able to do. The list is too long to mention them all. There were easy asanas like baddha konasana.
What happened over the years because I didn't omit anything?
1. My likes and dislikes changed with the daily practice. Garbha pindasana is no more a not liked asana, but a funny one.
2. I experienced that more than I think is possible. I only learned this because I did these impossible asanas. I didn't omit them. I was stuck there and tried to understand them.
Current difficult asana is kapotasana. MSch stopped me here. The effect: I really work on this asana now. I get always an adjustment here. It's not 'you stop here' and then you're left alone. I get always support!!!!! Usually MSch stands behind me (like a wall, hahaha) and I try to get deeper and deeper into the pose. Usually I manage it to hold the knees. Today my hands were below the knees. It's so much closer to my own feet. I become optimistic and work even harder on the impossible to make it possible.
3. I learned that the mind likes to judge the asana. Do I like it? Is it difficult? Supporting questions are rather 'How can I perform it?'
4. With time judging fades away: the attitude arises 'what needs to be done must be done'. No discussions more, no conflict.
For me my yoga practice is a mini world. I developed the attitude: What's next? Difficult? I don't care that much. Easy? I don't care. I don't like it? I don't care. I like it? Great. Today I'm not in my best mood. Why not, it's not a drama, nor is the opposite a drama. And I move on to the next task.
This is a relaxed life. The valleys are not so deep anymore, the mountains not so high. Life became a bit more relaxed.