As Nigel says, spare key marked " Spare" and I've taped it in a hidden spot on the bike.
Most likely it will stay taped there for all the years ahead.
If not, it would be because I've lost the main key while out touring somewhere.
Unlikely, but it could happen. When this does happen it's nice to have a hidden key on the bike/car. You don't have to remember to bring a second key, it's always on there.
Away from home riding means the oil is on. The hidden key gets you home. Its just a regular key, it won't turn the oil on or off.
As Ludwig pointed out, you only use the valve a few times per year at most.
It's mainly for winter layup.
With this particular setup, there is no need to add " turn on oil" to the checklist
I got on the bike the other day after having it sit for months with oil off.
First thought was, " Why isn't the key in the ignition?" Second thought was " Where did I leave the key?"
Third thought " Oh, right this is the bike with the key- valve"
I wasn't going anywhere on that bike without getting to the third thought.
Glen