Have you ever used all the stove burners at once?

I have used three of the four at once. No problem at all.

I don't do it regularly as I have a personal cooking rule that I only use as many pots/pans as people I am cooking for. And as I am usually going solo, I usually only use one pan.

And yes, my fridge and water heater were both running on propane when I used the multiple burners.