If you are talking about a nationwide real estate market, my assertions is: that a nationwide real estate market does not exist and the 'cycles' you see in the Case Schiller are the second and third order consequences of fluctuations in the greater national economy, which has demonstrated cycles. 

So if you raise rents by $100/month on an 8-cap commercial building, you have now directly forced appreciation by (100*12)/.08 = $15,000, whereas on a residential, it depends a lot on what your neighbors last sold their properties for.Of course, nothing ever works out that precisely in the real world, as caps also fluctuate, but caps are not as volatile as comps.

When it gets that low, it usually only stays for about a week, and then it’ll fluctuate between low 30’s-40’s.

Add the plausible cost of steel prices fluctuating, and people are not jumping at every opportunity (I, of course, don't know where your location is and the total possible value, this is a generality)   4.

That way, you can understand if yours is a seller's market and predict fluctuations in order to adjust your timing when listing your property (spoiler alert: we can't really predict the future, but we can certainly identify trends and be more prepared than others);2) Consider potential uses: Depending on the demand in your area, converting a 4-family into a 2-family or single family home before selling might translate into higher and more profitable offers.

NCREIF Real Estate Correlation to:Russell 3000 Index: 0.23Barclays US Aggregate: -0.24NAREIT: 0.13A correlation coefficient of 0 means that price fluctuations are not correlated at all.

HELOCs fluctuate with the interest rate so you need to forecast if you have enough funds to cover yourself in the event of hardships where the interest rate rises, rental rates drop, vacancy rates increase etc. 

If your payment after collecting one unit of rent is less than renting the equivalent unit then all is good because see item 2.  2) You get to write off the interest related to your living unit.  3) Markets fluctuate in value but San Diego historically has always risen over enough time. 

With cash you have great negotiating power, lower closing costs, higher income and the ability to withstand extreme market fluctuations.

When a tenant doesn't pay their utilities separately (which will obviously fluctuate in price depending on the season), they have less of an incentive to conserve resources and won't think twice to leave the AC running, lights and TV on, or take long showers, resulting in higher costs for you.