water to grain ratio

[SaintsValentine]

I read this somewhere recently:

"The way I determine how much water to use is the trusty finger method, which only works in my experience with any amount of rice over 2 cups. And I recommend you always cook 2 cups or more as a practical measure - this means you will have brown rice available for two or three days at a time. The only people to whom this does not apply are those with severe candidiasis or environmental illness, where it is better to cook the rice fresh every day. After washing the rice a couple of times add spring or purified water to the rice in the pressure cooker so that the level of water is at the first crease of your index finger as the tip of the finger lightly rests level with the top of the rice. This is your guideline."

Is this good advice?

Also, what if you're combining grains, like rice with barley or spelt, and so on? They all seem to require different amounts of water. This seems a little complicated to me ...