Cheryl,
I think it might be worth learning to do a full multi-unit analysis.
People who use those shortcuts already know how to analyze a property from top to bottom, and use those shortcuts as a quick tool to decide whether they should continue to analyze or just move onto another deal.
It's not that hard to mathematize (i made that word up) a few units, or any small multi-unit building, and there are even spreadsheets with cells built in to help you add your required profit, to pad or trend expenses, and to stress numbers up or down in future years.
Again, in my own opinion, if you're going to spend money on a few units you might as well know how to analyze those units and make an informed decision. Otherwise trying to figure out a shortcut is going to take just as much mind power as figuring out how to do the real analysis.
The easiest explanation of a multi-unit analysis for beginners is found in a book called What Every Real Estate Investor Needs to Know About Cash Flow... And 36 Other Key Financial Measures, written by Ralph Gallinelli. I don't know him and have never spoken to him, but I find his book really breaks down the steps in unit analysis very well.
http://www.amazon.com/exec/obidos/ASIN/0071603271/realdata-20/ref=nosim