Show the 30 degree bank.
Then teach how to maintain the 30 degree bank.
Every procedure in the world is based on rate 1 or 25 derees bank whichever requires the less bank.
If dealing with CPL and IR students 30 degrees as a maximum is standard SOP with commercial operators (for a good reason).
The traget AOB for initial medium turns should be 25 degrees when a suitable margin above the stall exists and 15 degrees when less margin is available eg while at climbing or gliding or approach speed. This concept translates into all future aspects of flying that the student may do. i.e. remember - Primacy!
The rationalle between AOB and stall margin can be well demonstrated during the stalling / spin avoidance exercises.
This basic exercise can then be further expanded in a later post solo exercise by explaining the rate 1 turn and the relationship between AOB and speed to acheive rate 1 which leads into turns using the magnetic compass / timed turns.
If 30 degrees is the traget AOB then most PPLs and CPL students will vary from say 25 - 35 with sometimes 20 to 40 being seen at times (based on visual attitude flying). 45 is a steep turn under JAR-FCL.
At the appropriate stage, turns at 45 degrees AOB can be covered and after that point, the student should be capable of turning at any AOB up to 45 degrees while also demonstrating the use of a suitable margin above the stall plus passenger comfort aspects as appropriate.
Remember that 15 degrees AOB is rate 1 at 80Kt and 25 degrees is rate 1 at 180. Most basic trainers climb at 80 Kt or thereabout so 15 degree bank is not far from rate 1. At 100 Kt rate 1 is 17 degrees. So using 25 degrees in a basic trainer is turning quite a bit above rate 1.