In the few times that it has happened, we've been able to fill the vacancy within a week or two.I may also have a different perspective because at 25, I had a failed business and moved across the country for a new job.

It is also your responsibility to try and find a tenant in a timely manner to minimize the vacancy. 

Some properties are in a position either through disrepair or tenant vacancies that they simply can not be financed at anything close to a reasonable interest rate.  

@Alan Asriants and I left out expenses like 10% for repairs at 5% for vacancies because I am so skilled at this I have never had a place vacate for less than one week because I keep them ship shape so it moves out.

Vacancies are a killer so having more doors allows for some diversification (having one vacancy in a fourplex is 25% vacancy versus a SFR vacant and that's 100% vacancy).

Another GP is losing money is because their PM is not good,etc,etc..Regional issue, it's known that in regional issue, due to supply/demand mismatch and miscalculated of rent growth, the vacancy rate of one region is faster/slower than the others.

I would recommend getting a place where foreign students stay, there are pretty much no vacancies this way.

Not saying it won't be a good deal but you have to know that vacancies can last longer the lower the population.

For example, there's a 1950 duplex for sale (West Palm Beach, FL) for $500k with each tenant (MoM) paying $1,500 = $3k/moThe mortgage is $2.8k/moWould this be a bad investment because you would have to factor improvements and possible vacancy?

If there are vacancies how does one typically find tenants for industrial space like this, just list it with a commercial agent and let them do their thing?