There absolutely IS such a thing as optimal kerning. But, my take, as someone who has done it many, many times is that “optimal” means you do it, rather than you don’t do it.
In fact, there’s even a commonly used formula for it, though–to the best of my knowledge—not written in code. Good designers are taught this formula at one point or another. (And once you know the formula, you know who hasn’t been taught.)
This is probably going to be a way longer answer than expected, but if anyone wants to take this and do an excellent job automating it into design software, I will be a huge fan.
A) First thing, just to make sure we’re all on the same page:
Kerning = the space in-between two letters. ONLY two letters. Tracking/letter-spacing = the space between all of the letters in a body of text. And when altered, applied to an entire body of text.
B) Second thing: Defining “optimal”
Most typefaces/fonts are designed for average use. That is to say, its optimal state is as paragraph text. When you make text really big, like in a headline, sometimes weird spaces show up between letters. These spaces don’t matter at small sizes but make the letters look cheap and amateurish when they’re big. And, they look unprofessional when the word is important, like a logo. So, kerning manipulates the space between letters to make the word or words look more professional and considered.
(This is the crux of designers’ analysis of Alphabet’s logo—it’s freaking Google. It’s worth getting it right.)
C) Third thing: The Formula, or How To Kern
Here’s the secret: it’s hard to perfectly kern something when you’re looking at the entire word. So, don’t look at the entire word. Look at three letters at a time. Cover the others up with paper (a sticky note works well for screens). For those three letters, make sure that middle letter looks balanced and not like it’s drifting to one side or another. You can manipulate that space by moving either the first, second, or third letter. You can make the whole set wider. You can make the whole set narrower. You’re in charge. Just make it balanced.
Then, shift your three letter “window” to the right or left (I recommend right) by one character. Moving ONLY that new character, make it balanced with the two from the original set.
Then repeat that process until you finish the whole word. And then go back and adjust the whole thing all over again if it still looks unbalanced.
There’s a reason you typically only kern logos or reasonably short headlines. It takes forever.
D) Fourth thing: Kerning affects the “vibe” of the logo
Tight kerning where the letters touch or almost touch each other feels big, corporate, and sometimes a little dated. Think: FedEx, Newsweek, Infosys, or Oracle.
Really wide kerning where the letters are quite far from each other tends to feel futuristic and elite. And, these are almost always in all-caps. Think: Uber, Prada, and approximately one million hipster logos from 2013. And take my word on this one, you should just never bother with a spaced out word or logo that’s upper and lower case. Just let that idea go, please. Not worth the aesthetic agony and designer backlash.
Last but not least: Reasonable kerning widths, where there is space between letters but not tons of space, feel like the “norm core” of kerning. Which (in my opinion) is a good thing. And this is what Alphabet’s logo is going for. It’s neutral, and feels humble, but smart. More down-to-earth than wide kerning, and more youthful than tight kerning.
Pro-tip: Reasonably normal kerning widths in all caps can look amateurish. Consider making the spaces bigger (more Uber-ish) or switching to upper and lowercase.
If you read through all of that, thank you for your time.
My tip to someone who would like to automate this process using a dataset—make you have data from different type sizes, because type size is the biggest determining factor in “optimal” kerning.
Good luck!