When calculating a deal, do you calculate at the long term rental rate?

[Mark Gould]

New and trying to find which lane to pursue. 

I’m curious when you are calculating your deal, do you go at it the same way you would a long term rental? So for example, if I figure mortgage is $1000, and when I calculate everything I get  enough to cover everything, but no real cash flow and not what I would normally look for in a long term rental to consider it a good deal. But since mid term brings in more, would I change my standard, or keep it the same?