My rice method works for two people and falls apart for four

I have a small-pot rice routine that is very reliable for two servings. When I double it in a larger pot, the bottom gets softer while the top is still a little firm.

I assume simply doubling water and time is the wrong way to scale because evaporation and pot shape do not scale with the rice.

I am going to try keeping the same rice-to-water ratio but using a wider heavy pot, bringing it to a boil, then using very low heat and a longer rest. I am curious whether people change the water ratio at all for larger batches.