As organisations adopt large language models (LLMs) for discovery, decision support, research, and customer interaction, interest in monitoring AI system behaviour has increased. Many existing tools rely on high-volume, single-turn API queries to observe outputs in controlled conditions. These tools provide meaningful operational value but capture only one dimension of model behaviour. Real user interactions often unfold over multiple conversational turns, incorporating refinements, tone variations, emotional cues, and personalised context. This paper outlines: (1) what API-based monitoring reliably measures, (2) where its methodological boundaries lie, and (3) how multi-turn reasoning analysis provides a complementary lens for governance, drift detection, and behavioural assurance. The analysis does not prescribe specific regulatory obligations; rather, it clarifies methodological distinctions and presents the AIVO Standard as a structured framework that organisations may use when deeper behavioural analysis is required.