A lot of people don't take transfer taxes, property taxes and capital gains into their equations. but I do.So, I look at trends.

Your fourth point stands out to me: having an insider's view and watching how your specific market trends is a difference maker.

But the markets I follow still have very low inventory compared to demand, and my understanding is that the Hyper Supply phase has two defining characteristics: New construction (which is happening) and increasing vacancy rates (they haven't yet broken their downward trend). 

I don't think we can underwrite off the past few years trends.

There are four sections: national trends, state trends, city/area trends, and neighborhood trends.

The reason this trend tends to happen, from what I've seen, is because there is massive industry (jobs) in LA, and in the greater CV area there outstanding schools, safety, weather, and general quality of life.The SFV, however, has neither incredible industry/jobs nor incredible safety/schools/weather/QoL.

Your goals to focus on buy and hold properties seems sound, and getting started at a young age will allow time to be on your side, to take advantage of some gains due to inflation, changing market conditions, historical trends and your experience in the RE market.  

As for if an area is on the rise or on the decline you have basic demographic trends.  

You are correct property values in Phoenix have drastically appreciated over the last year, Tucson seems to be following a similar trend.

Looking at housing trends over decades you would expect a down cycle every +/- 7yrs.