Hi,
The time spent in any exercise/exercises is more relevant than the number of reps. It takes qi about a half a hour to complete a cycle within the body, and that unit of time is relevant to the practice. One unit can be referred to as a season and four seasons a complete year. Anything, or more or less, all falls into good, better and best. In other words, good is the worst you can do.
You don't have to be concerned about creating a specific balance regarding how long you do one exercise versus another. They all have their own effective means of clearing energy blockages and stimulating qi flow. It is important to close each session with harvesting qi, and bouncing beforehand is good. How you frame your session , or open and close the session.
In the beginning, I followed Master Lin's lead as given in the tapes or CD's.
Love,
gallen