For example the rent should be 1-2% of the sales price, but that fluctuates greatly and in a D neighborhood you can get 2% but in a major city you most likely will not even get 1%.

Power and gas will fluctuate but water tells the real story.

It appears you had several anomalies last year, but if you have several anomalies in a single year, it's not unreasonable to assume that they aren't really anomalies and you'll experience other similar income/expense fluctuations in subsequent years.

Then there is the fact that material and labor costs fluctuate fairly significantly at times which would change these numbers. 

But, just like stocks, if you hold on through the ups and downs you're more likely to end up on top - turnkey is buy-and-hold, so be prepared for market fluctuations.

Maintenance is a fluctuating variable, but there are indeed favorable hedges offered at reasonable rates well below 50% of net.

And you have the flexibility to adjust as the costs fluctuate.

When you invest with a Turnkey company you are investing passively and allowing for fluctuations is going to be important. 

I have been battling with attempting to keep my home by way of filing bankruptcy since my income continued to fluctuate.  

(Vacancies, Market fluctuations, or repairs)