In example 1 for a lower end rental, IF the boxes are in good shape and the faces are dated, changing only the fronts makes more sense.Also when updating go for classic not fashionable as the latest fad changes faster (hopefully) than your upgrades. 

As already mentioned above, if you go the amazon route you will have to be nimble to keep up with the latest fad sales or whatever as fads are really the only way to get a foot in the door (vs. trying to sell a staple).

Tiny homes are a fad.

The fad over the past several years has been to flip with 100% financing using gap funding.

One client's dollar is just as important as the next client's.Don't get too wrapped up in marketing fads.

This was caused by deferred maintenance and the tenants' diet.  

While Teslas are a fad and kind of cool, especially in California, they only bring you admiration from people you shouldn’t care about.

Rooftop solar requires 0 gallons/year.To see how your diet impacts the climate, there's a fun calculator here: https://www.bbc.com/news/science-environment-46459714

Like alot of things in life it easy to make excuses why you shouldn't do something or should wait to start something until later (investing, dieting, exercising).  

This book is more for the academically and analytically inclined, but it is chock full of industry keywords, real-life case studies of true investments, and it dives deep into an understanding of real estate as a real investment, and not just a passing fad.