At our first company, the team spent roughly 1/4th to a 1/3rd of their time purely on front-end experiments … for parts of the HTML and CSS spec that haven’t released yet for browsers that didn’t exist yet. 

There was no customer asking for this, no TAM, no current user problem to solve. Just knowing that every line of code was an inevitable future to come.

That work eventually landed us Apple as a client which eventually prompted an Apple acquisition offer that led to our Twitter acquisition.