My 2¢. As long as a switch is on and remains on, it really doesn't matter.

Consistancy reinforced by cross-check methodology serve me well. But consistancy is easily corrupted dependent upon the type of switch one uses, and whether the same type of swith is used throughout the 'fleet'.

eg: I use exclusively OEM JR "D" type switch harnesses with integrated DSC capable charging socket and sliding socket cover. I consistantly mount them horizontally on the fuselage side opposite the silencer, or where the silencer is directly underneath the fuselage, by preferred convention on the left hand side of the fuselage so that aft is on.

As these switches are labeled on and off, and to avoid confusion with charger/DSC lead connector orientation and polarity, I always mount the switch so the moulded labeling is upright. This results in on being forward when the switch is mounted on the right hand side, and aft when the switch is mounted on the left hand side, but the slider positioned immediately adjacent its charge socket is always off. This convention is easily visually verifiable relative to the orientation of the DSC/charging socket and serves me well. I've not found either the forward or aft on position offers any advantage/disadvantage. On is on and off is off, so I can only presume the switch neither knows nor cares whether on is orientated foreward or aft. Mine certainly haven't said anything to me about it yet.