Well, I'm going through the audio lessons again. This time I notice a statement that Master Lin says that if you stop your practice then your channels close. No more details than that. Nothing about how quickly, or if the stay closed.
I believe this is said in connection with the need for consistency in one practice.
Master Lin also mention at times things opening and staying open.
My experiences and thoughts are as above, but I felt it necessary to pass on the information.
You are perfection.
Iam2 
