Set a frequency cap on a Meta reach ad set

Limits how often one person may see the ads in a reach-optimised ad set: at most max_frequency impressions every interval_days. Use when: the ad set optimises for reach (or ad recall) and frequency is climbing — the usual first response to creative fatigue on a brand campaign. Do not use on a conversion, traffic or engagement ad set. Meta only honours a frequency cap on reach buying, and setting it elsewhere either fails or does nothing; the preview refuses rather than pretending. Do not set an aggressive cap on a small audience: Meta simply stops delivering once the cap binds, and the budget goes unspent. Returns the ad set read back from Meta with the cap that is actually in force. If the user wants "less repetition" on a conversion campaign, the honest answer is to refresh the creative or widen the audience, not to cap frequency.