You can wire your accessories to be always hot if you choose. Nothing wrong with doing it that way at all. I currently have my machine always hot. It does live on a battery tender when not being used though. No reason other than I already placed an order for switches and forgot to get it. I do have the solenoid, and it will be wired to a DPDT switch at some point.
Edit, What is best for you, is best for you and your uses. I don't have kids messing with my machine. No one to leave the lights or radio on by accident.
Edit #2, If I am away from my machine for any length of time, and am worried about people messing with it, just above circle 1 is a circuit breaker. I can trip that and essentially kill my second battery.
What he said ^ ^^^^^^
Next thank you, because keeping it clean and wired tight was impotent to me.
These are the reason I thought it was a good idea to be able to switch the second battery on/off without key on:
A. I've got a 7 year old. He plays with switches. I've seen photos of people who leave their winch hot all the time, sometimes 24/7 others only when the battery was on and the winch was accidentally bumped or activated "IN" and it sucked the bumper right into the winch ripping stuff up. Three things need to happen for my winch to operate:
1. either key on and/or a dash switch on for second battery
2. power on switch for the winch
3. operate winch IN/OUT
Hopefully those redundancies will prevent an accidental activation.
B. I almost never have to worry about draining the main starting battery when I have have "key on" to get an accessory to work and the hour meter isn't spinning for no reason. When you key on you can hear lots of buzzes and whirls so the battery is being used preparing for a start. I can stop that from happening by using the switch to the isolator switch to only have to the second battery on with zero draw from the main battery. So I can use the lights as long as I want with the engine off and never worry about a dead battery.
C. Convenience and peace of mind knowing the accessory side is shut off from a dash switch. Slight coolness factor.
Since this photograph I made one change I'm surprised no one tore me up on. The winch red power line going to the 100 amp fuse panel cut the available amps available to more than a 1/3 less of what I could have directly connecting it to the second battery. That has been changed and now directly connected to the second battery positive post.
This is my build page if you want to see what I used, where I got it and what I did:
P1000 - OnTheJob's P1K-3 Build: "The Pie-O-Near"