Andy, I always try lighters a few times before I trust them.. Like you I also immobilise the gas button! Great minds think alike..

I should add I have two processed flint sticks, which also go in my kit, it's just the butane lighters will light a gas stove in the wind unlike a flint stick! I added the lighters to my kit after failing to start a fire when some squaddies were nearby to chuck me a lighter! (Doh!!)