Lmao tell me you have no idea what you're talking about without telling me. You probably prompted an AI that got confused and tried to tell you you'd get 5-10 min of burn time out of a small set of tanks.

First off the dude in the pic is welding. You can see the grounding clamp on the back of the truck. Welding sparks are white, torches are usually orange. And to get a welder to hit gas inside of a tank... 1-2 seconds.

If somehow those are torches in the picture, you can get oxy torches through the (up to) 2mm thickness of those tanks in no time (maybe like 1-2 seconds). Here's a video of a guy cutting though 1/4" ~6mm in seconds, for reference: https://youtube.com/shorts/JLijFDI-qgA

I could be remembering wrong, but basically any remnants inside are unpressurized, so they're all vapor, easy to heat since there's less thermal mass, and ready to light if there's any oxygen.

Because the assumption that there's no danger, coupled with the fact there's now oxygen inside the tank, much more likely to be near the flammable or explosive ranges.

When full or in use you expect it to have fuel in it and usually take more care (obviously the welder isn't), and if a leak catches fire it then turns into a torch, until the tank overheats and bleve's (very unlikely that you don't notice the torch before the bleve)

The big risk of full is, you might have a steady leak that stays in the area, and then you ignite it somehow. But the likelihood is very low that it would get to the flammable or explosive ratio in open air like this.