> On the text end of the spectrum you have high clarity, but it takes longer time to take in and find the one you are looking for.
I just don't believe it takes a longer time to find the word "Defrost".
> These are good if you rarely interact with the them and it's in situations that aren't urgent and you can't or don't have to train for.
Take a look at aircraft instrument panels. They are very much designed for clarity and to be usable in emergencies, usually the hard way. They use words. Altimeter, Airspeed, Vertical Speed, etc.
> you might be able to guess pretty well what they mean on first encounter.
Not me. 3/4 of icons in new cars I don't know what they mean. Most of the ones on my iphone as well. Thankfully, sometimes they use words like Save, Edit, Library, etc., and I no trouble with them. The ones on the app screen thankfully have a word under them. After all, look at that weird stick icon, which has "App Store" written under it. Or the Photos icon. Apple has even given up on the trash can, reverting to the word "Delete".
> but will be much faster on future usage
Pilots and airplane cockpit designers evidently disagree.
> drivers
Quite a lot of concepts have no picture that makes any inherent sense for it. Like "60 miles per hour". Or "stop". or "yield". You can certainly get used to a red octagon meaning Stop, but for someone who is not trained on it, the red octagon might as well mean "pizza next exit".
I lived in Europe around 1970, when they were transitioning from the old signage with words to the new ones. They wanted to harmonize the signs. The trouble is, if they used words, it was a matter of national prestige which language was used. Using icons was a solution to the political issue, not a readability one.
The American stop sign was settled on because nobody could agree which European stop sign would be selected, so the compromise was none of them.
To sell this all to the public was the notion that icons are better, but it was really political.