I guess skipping a few gears between shifts because you don't know how to shift sequentially was a bigger deal on my 12 speed 40 years ago than it is on a 20 speed these days . Still I do a lot of double shifting ; meaning I shift the front and the back at the same time . This is also a lot easier these days with modern shifters compared to double shifting with one hand on downtube levers that I started with or even with the Suntour bar cons on my Dawes that made it lot easier than the former .