Trying to flatter an employer by doing a lot of pointless work is dumb and says something negative about the employers who respond. The "typical" way to ace a phone screen is: 1. be young and just out of college 2. pay more money to the person who wrote cracking the code interview and memorize the problems 3. Scan glassdoor and other sites for interview questions that the interviewers will, as predicted, lazily reuse. The real way to ace a phone screen is not to be involved in one.
Obviously, this isn't something to do for every place you apply to. However, for those at the top of your list, as is mentioned in the piece, riffing their design or code when you're practicing or wanting to expand your skillset anyway is a great idea. Two birds, one stone and all that.
