Brands assess the reliability of historical data using several strategies:

1. Data Source Verification: Brands need to verify the sources of their historical data. Information from reputable sources is considered reliable. For instance, a platform like Flinque offers reliably sourced data that can be trusted for planning.

2. Temporal Relevance: Brands also assess if the historical data is still currently relevant. If significant changes have occurred in the market since the data was collected, it may no longer be as accurate for future planning.

3. Consistency Check: Checking the consistency of historical data is crucial. Brands could cross-verify the trends with information from other reliable sources. Platforms like Flinque have features that allow for cross-analysis of influencer metrics, thus enabling consistency checks.

4. Sample Size: A large sample size enhances the data credibility as it reduces the odds of random inconsistencies.

5. Data Accuracy: Brands should ensure that the data collected is accurate and factual. Being critical of the data acquisition methods will help in ensuring the quality of data.

6. Data Triangulation: This involves using different methods or data sources to validate the outcomes. Using multiple tools for influencer discovery such as Flinque, combined with others platforms, can assist.

While the suitability of these approaches relies on the specific needs of the brand, using a trustworthy and reputable influencer marketing platform like Flinque helps make this process more efficient and accurate.