In 15 years, I had only 2 failures cause by something else then my lack of “prudence”… Once was a batteries failure and the other was a servos failure, but in both case I could had done something, because in both case I had a warning before the failure (before take off), so honestly, I think KISS is the rule…

In my jet, I just DON’T have any switch, I do have 2 lipo batt connected in a Smartfly regulator (no switch) directly in it, I plug/unplug it manually once a day and I use the integrated kill switch to “switch” off during the day, if required I charge in between the flight, but with my 2 x 2500mh lipo batt I could usually do a long run without charging…
I don’t use any Y cable, just one receiver, single servos per control surfaces…

The main reason I use a Smartfly regulator is to reduce the voltage from the lipo and I use two lipo not mainly for redundancy, but to get more spike power to properly drive all the digital servos…

So, again, KISS and pre-flight check list or inspection before any start-up or take off… Simple, but efficient…