There are 2 main contributions to this ROI — net rental yield (NRY) and (AA) asset appreciation.

Q: Pick an arbitrary target AA like $1 -> $4. How likely? What could derail this ROI?
A: My Short answer: possible in some developing countries but plenty of uncertainties.

I feel NRY is less glamorous but more stable, predictable and reliable.  I feel as investors we had better focus more on rental income vs TCO including mortgage, tax, maintenance, commissions.

In my view, AA will take care of itself and almost beyond our control, just like stock prices. Many factors can derail AA, so I don’t want to micro-manage. As a long-term and casual investor, I’m too busy and lazy to monitor it.

Location? I hear about high AA in top China cities. I feel such price inflations are often driven by Chinese investors. I feel Singapore, Beijing … PSM prices are already very high by multiple criteria[1] and less likely to x4 in my life time

[1] by comparison with world cities; by living standard; by national income level. Also by rental yield — See https://tanbinvest.dreamhosters.com/2016/09/11/rent-yield-cnsg/

Usually property prices rise steadily most of the years but in rare years shoot up or collapse with or without a recovery. These jumps are critical but hard to predict.

Across countries, in most “normal” economies, property tend to appreciate. Therefore the exceptions are worth investigation.

Many (esp. the Chinese) feel AA outweighs NRY, but annualized growth rate of AA could be 10 ppa. NRY could be 10+ ppa.

Liquidity is the biggest advantage of NRY over AA. This makes NRY a more relevant factor than AA for retirement and pre-retirement (like age 45).

Patience — AA can require a long wait. NRY requires no impatience.

Q: is it important to set a target sell price in case the market overheats?
A: It can be important. However, If NRY is good, then the longer we hold it the better.