I just use the 3 position switch when I want to cut my engine.
I've made a combination between the idle up and the smart fly l, ignition cut off. The upper position is on the middle is lowering the idle just beneath the butterfly position which is about to cut, it's for taxing and the Lower position is deactivating the ignition.
All my switches that I'm using are on the left side where the throttle is so the mindset is, throttle ... Kill switch and idle up.
As for the second switch, it's just above the throttle so when I'm flying and doing either 3D or imac it won't interrupt my flying I'm still holding the ele and ail which are the most active surfaces.
What ever you do, make a pattern, mindset that will be easy to use and to remember it needs to be as a reflex.
Imagine not flying for two weeks, with all the planes you've got you'll need to do a log book which switch activate which surface...well you can make it easier with the method I've just wrote...make them all the same.
You can split the transmitter in two, the left is everything that is related to the mechanical staff i.e. Engine, doors etc....
The right is everything related to the surfaces.
When you move the switch up the things go up...down is down...
Right is open, left close.
Up is positive, left negative
And so on...