Most budget benchmarking exercises start with a survey report from a consulting firm and end with a slide deck that justifies whatever number the CFO already had in mind. That is not analysis. That is confirmation shopping.
The aggregation problem nobody talks about
When a benchmark report says companies in your sector spend 8.3% of revenue on SG&A, that figure pools together firms with different go-to-market models, headcount structures, and geographic footprints. Applying that number to your own budget is like using the average shoe size to buy footwear for a specific person.
Common mistakes experienced teams still make
The first mistake is treating percentages as targets rather than reference points. A ratio tells you where others landed, not where you should aim. The second mistake is ignoring the denominator. Revenue-based benchmarks shift dramatically when one division has a one-time contract. The third mistake is benchmarking total spend without segmenting by function or cost driver.
What actually works instead
Segment your benchmark cohort by business model, not just industry code. Compare cost-per-unit-of-output rather than percentage-of-revenue. Validate any external benchmark against three years of your own internal trend data before drawing conclusions.
Peer data has a place in budget planning, but only as a sanity check, not as a starting point. Teams that reverse this order consistently build budgets that look defensible on paper but perform poorly in execution.