> Smartphones cannot cheat Fitts's law, they will always be much slower to use than desktop computers.
Why would Fitt's law have anything to do with smartphones being slower? If anything, it is the opposite.
A phone screen is smaller, so all targets will be close to each other - and Fitt's law says these will be faster to access than on the large screen of a desktop.
BTW, that's also why interfaces on mobile have big icons with lots of white space around them - Fitt's law says that bigger targets are faster and easier to reach.
To fit equivalent desktop functionality to the smartphone you have to make targets either smaller, which will make them impossibly slow to use, or hide them behind other targets, which again will make them slower to use requiring hitting multiple targets instead of one. I.e. can't cheat Fitts's law.
> targets will be close to each other
Close to each other targets are effectively smaller targets, because the area you are hitting them with has some dimensions and has to fit in a smaller area to avoid hitting closer targets too.
But in desktop everything will be far away, so it doesn't provide any advantage either. And hitting the targets that are visible will be faster on mobile.
Why would Fitt's law have anything to do with smartphones being slower? If anything, it is the opposite.
A phone screen is smaller, so all targets will be close to each other - and Fitt's law says these will be faster to access than on the large screen of a desktop.
BTW, that's also why interfaces on mobile have big icons with lots of white space around them - Fitt's law says that bigger targets are faster and easier to reach.