With time comes skill, so goes the saying. In the training of Tai Chi short term results are possible but they will be rough around the edges.
If you want to have refined skills then you need to keep working on the small details for as long as you need to, one small step at a time.
When you stop worrying about how long the learning takes, sit back and enjoy the ride, time can fly before you know it. Then comes the day when your skill begins to manifest itself. Things that seem difficult to do previously, to understand what is happening, suddenly becomes doable, the picture clearer.
Most of the time the following factors stand in the way of your progress :-
a) Not enough time to practice
b) Not consistent practice
c) Did not pay close enough attention to the details
d) Fixed mindset that cannot see any other way except the habitual way
e) Current unusable or incorrect physical habits that are wrong for the principles
f) Cannot see or understand what is really going on in regards to the requirements
This is why the student who will master the art is the one who really wants to have it and will not let the lack of time to practice to stand in his way. Instead of giving excuses he will find the time and he will practice daily as much as he can.
The student will also give up on past unworkable habits. If you keep hanging on to your old habits that impede your learning and actual progress then expect not to make progress. You should never go to a new teacher to learn the same impractical things. Instead, a new teacher should present a new view point, that can perhaps jolt you into seeing things clearer, able to offer an alternative path to success.