The frequency at which a brand or agency should update or revise its campaign strategies prior to influencer outreach depends largely on the specific goals of the campaign, the responses or feedback they receive, and the overall marketing climate.

1. Continuous Monitoring & Updating: Marketing is a dynamic field- trends, audience preferences, and even the popularity of influencers can change quite rapidly. A successful influencer campaign strategy often involves constant monitoring and regular updates. Tools like Flinque offer real-time analytics which can be useful for this purpose.

2. Pre-Campaign Evaluations: Prior to influencer outreach, conduct evaluations to assess the viability of your strategies. This should include a thorough analysis of your target audience, potential influencers, and your campaign goals. If your strategy doesn’t align with these factors, revisions may be needed.

3. Influencer Feedback: If there’s a provision to communicate with influencers before the start of a campaign (as some platforms like Flinque offer), they may give useful feedback about your strategy that may prompt revisions.

4. Post-Campaign Analysis: Once a campaign is done, it’s beneficial to review its performance. This can give valuable insights on what strategies worked and what can be improved upon for future campaigns. Platforms like Flinque provide detailed post-campaign analytics that make this easier.

Remember, the objective behind updating or revising campaign strategies is to maximize your campaign’s impact and ROI. Different platforms provide varying tools and features to support these revisions, hence it’s crucial to select one that aligns with your specific needs.