50% Rule clarification?

[Dave Versch]

Can someone give me a definitive answer on the 50% rule? I understand the concept, that your expenses should only equal 50% of your gross rent in order to get positive cashflow. But which expenses are included in the 50%? PITI for sure, but how about maintenance, vacancy allowance, property management, and capital improvement? And if the answer is that I should include all of those in the 50%, then why should it be a 50% rule? Why not an 80% rule if we've already accounted for all possible expenses? (I'm assuming the tenant pays all utilities.) I'd be perfectly happy with $200 net profit on $1,000 gross income every single time. Is the other 50% being budgeted just for unknowns and net profit, or am I missing something?