Hi,
Sorry, just seen your reply. I managed to figure out that I was spraying the can too high above the lighter. The spray is white when that happens but turns blue if it's held lower. It was driving me mad as it worked sometimes but not others. Having figured that out I managed to survive for 5 minutes and get out!
As for the refill cans, after one appeared on the van during a game I knew what I was looking for. On hindsight I should have realised they looked the same as the can in my hand! After a few plays I did use the same tactic you mention - stay next to a refill until you need it and then go looking for the next one. If anything, I now think you should have less spray in the cans to make it more difficult and/or make the lighter go out more (that made it more creepy).
I'm playing on an Oculus Quest2. I prefer free movement rather than teleport.