There are many debates on the dangers of over-teaching. That is, providing substantially more information than students need. Unfortunately, over-teaching can adversely affect the sale of future courses. This is for several reasons.
Knowledge saturation
If a course covers too much information, students may feel they have learned all there is to know. This can reduce the desire for additional learning.
Diminished perceived value
If students get an overwhelming amount of information for a single price, it diminishes the value of additional training. Why should students pay for additional courses if what they have already learned is more than enough?
Reduced need for progression
Most diver training programs are designed to build upon what students already know. If students get too much information up front, they may feel they skipped essential steps. They may also feel they missed out on the opportunity to progress incrementally. So, again, they are less inclined to continue their education.
An overwhelming learning experience
When you bombard students with too much information, it can result in cognitive overload. They may struggle to retain and apply what you taught them. This can result in an unsatisfying learning experience and discourage participation in future courses.
Edit what you say
You and your instructors should critically examine the body of knowledge you cover in your courses. Separate the need-to-know from the nice-to-know, as well as the utterly useless. Throw out anything that is not essential.
Doing so will create a more effective learning environment. And in the process, you can promote additional training more effectively.