My biggest frustration as a teacher, if I have any at all, is getting across the idea that we are all different and that is OK. I don't expect everyone to be able to do the same things the same way. I don't expect anyone to progress at any speed other than what is typical for said person when he/she is doing his/her best. Our bodies know what they need--much better than we do, much better than our teachers do. It is sad to me to see students who think they are struggling, and are holding up the rest of the class. First of all, struggle is a mental construct. You only struggle if you believe you struggle. Second, there is no holding up the class, because there is no where to go. The benefits of practice are found in the practice, not at the end of practice. No one is or should be in a hurry. If they are, they have also misunderstood the nature of this practice. If I have said it once, I've said it a million times: the means are the end.
The way to progress is through diligence, humility, and surrender. That includes surrendering expectations. We should all just go with the flow, flow with the wind. Take a step, then take another. If you feel the pace of things is too fast, slow down and go at your own pace. If you think the pace of things is too slow, slow down and look really close at every single movement, every breath, every intention. You may find it's not going slow enough.
Taiji-Qigong practice should be fun, relaxing, and energizing. Let it.