In this case, short term market fluctuations don’t matter much.If they can’t get that sort of income, they’ll need to rely on general market appreciation - whether through inflation or real price increases - to drive a solid return on invested capital.  

Then, they will resume their long term, inflation driven trend, with 10-15% fluctuations off that level over the course of a few years.

Based on your quoted prices, it seems like you're hovering around 1% rent:purchase which means minimal fluctuations could be risky at throwing you below that.

Insurance carriers have different risk pools and constantly re-evaluate their rating based on those pools, so the rates at any one carrier will naturally fluctuate on any particular type of risk.I think it's a good idea to insure a property for replacement cost, at least at first.  

Although I have a problem using daily stock price as a true measure of volatility, at least daily price fluctuations is something resembling volatility.

There could be fluctuations in any case.

And when talking to the employer, I always ask if the job has seasonal hour fluctuations and how many hours a week they typically work.

People may lose jobs and the economy may suffer in general.There are all kinds of fluctuations and variables that will have major affects on doing business.

One nice aspect of multi-families and long term investing is that they weather market fluctuations better than SFHs, so even if your market goes down, you'll have tenants paying until one day when value is back up.

The most practical advice I can give is to try to answer the following questions:How well I am positioned to absorb market and interest rate fluctuation?