You ask if there is a "shorter" #Bookofwhy, and I assume you want to get the technical meat w/o reading the stories. Yes, there is. If you take a look at Section 2 of ucla.in/2mhxKdO, you will find the whole book summarized in 3 pages. But it must be supplemented
with the toy problems of Section 3. No matter how many books one reads ABOUT economics, shying away from solving toy problems would leave one where econometrics is today -- two decades behind the time. Plus, it is fun to see important methodological problems escaping their
textbook handcuffs and rejoicing game-like solutions. I therefore recommend: do not skip the toy problems in ucla.in/2mhxKdO and their solutions. Try one - its better than reading a whole book. Among the easy ones: Can your research question be answered using OLS?