Yup, I use one pedal all the time. In Normal mode, left paddle for full regen and the car does all the braking and accelerating for you.
I set cruise control according to the road speed signs. Accelerate to what speed I want an right toggle up to set cruise control, brake as necessary. Braking switches off cruise, so just set it again. My car is my23 and a year old.
Its the most comfortable way to drive it and nothing to do with efficiency.
I did not get the I5 to be efficient. I never did concern myself with range in my petrol car or the I5, it is meaningless. The I5 surpasses my previous cars by an enormous margin and in every respect.