let my currency go a few years ago. Got it back, and let it go.
Lots of floks like the "cheap" biannual. I don't.
A few things I found important, that I crossed swords over with others were level of proficiencey/ability.
I got in trouble by a boss for making a student sick. This student had gotten his private, twin (in a beech tavelair), and was working on transitioning into a V-tail bonanza. Simple, same basic plane as a Travelair, but one engine in front.
During stalls I noticed that the student loved to look at instruments, (cavu day), so I suggested he look outside. No change in behavior. Next I covered up the AI, HI, and airspeed. He said it was'nt 'fair'. He was totally uncomfortable flying without instruments.
Next on unusual attitudes he had the same problem, only this time when I had it pointed down, in the yellow arch and gaining speed he acutally could not immediatly look outside and recover without instruments, (still cavu). He got sick, I got in trouble for not being nice.
As an instructor I consider that a SEL rating is actually good for anywhere, any plane meeting signoffs, (high performance, retract, etc). So even if you live in the midwest with nothing taller than a cell tower to hit, students should know how to mountain fly, be ready for big winds, and have respect for aircraft they may get the opportunity to fly.
If they can not do the basics, (fly the plane), great radio work, instrument proficiency, knowing systems front and back will not help. In a V-35 bonanza pointed 10 degrees down with 3/4 power banked 20 degrees, trust me, it happens fast. If you dont pull power while leveling wings immediatly, you probably will bend something, if not break it and yourself. Does it matter if it was fair?
For all that, I like instructing friends. It is fun and rewarding, also keeps you sharp. And yeah, they are right, Don't relax at all. Sometime someone will shut the fuel off on you, or do something just as corny.
(are you sure you want to teach your own son????)