50% Rule vs. Applying Percentage for Expenses

[Zachary Sales]

When analyzing deals, is it better to apply the 50% rule to a deal, or go through and apply a certain percentage of rent to anticipated expenses, being Vacancy, Maintenance, Capital Expenses, and Property Management? I have been applying a 5% vacancy rate, a 10% maintenance, 10% cap expenses, and 11% property management fee when analyzing deals. This usually ends up getting me better numbers (more cash flow) than the 50% rule. Which, now I am wondering if it is the wrong way to analyze deals.