CVTs have all the gear ratios between a set low and high speed gear ratio.
The Corolla CVT goes from 2.480 to 0.396 with a 4.761 final drive ratio.
The six speed auto in the Cruze has 4.58, 2.96, 1.91, 1.44, 1, and 0.74 for gear ratios, with a final drive ratio of 3.53, for comparison.
When automatics get over 5 and 6 speeds, the extra speeds are more overdrive ratios. CVTs can match those overdrives, but outside Asia, many don't care for how they drive. Which is why many CVTs have pseudo speeds; to make them drive more like a step transmission. There is also the issue of how well a CVT will hold up a true work truck.
When you have virtually infinite ratios, you can use the transmission to control engine speed, while maintaining the ideal (high) load, instead of choking off atmospheric pressure to control engine power production, with a throttle plate, which is very inefficient.
These ideas appear good on paper, but truth be told, all the 8+ speed boxes you see on the German, Japanese cars here make very little difference to the fuel numbers. I thinks it's better to have fewer gears and be in top gear at as low a speed as you can afford. They tend to get slated by the press too, they are over fidgety, flapping around changing gear all the time at lower speeds etc, almost as annoying as a CVT.
The Prius CVT is awesome! I still drive the 6 speed manual diesel Honda CR-V once a week, which is a nice drive, but I definitely prefer the CVT. If you ever have to boot it, it does lose the super smoothness - but no more than as you charge up through a gear in a manual.
As for being in the highest gear asap, I found that to be a myth in the i20. You could easily drive in 6th when you were doing 50, the "eco" shift indicators encouraging you to do so. Yet the scangauge, with proof at the pumps, showed often staying a gear or two below top gear was actually better for economy. You'll have 6 in yours will you Paul?
There is more to it than meets the eye. In general an engine operates most efficiently at the speed at which it produces maximum torque. It produces maximum torque at the speed at which its internal losses are minimum. It will pull at lower speeds, but its efficiency will be lower.