When ceilings have beams creating pockets, a key concern is:

Smoke detector spacing is based on standard coverage assumptions and adjusted for ceiling height, configuration, airflow, beams, obstructions, and corridor geometry. The goal is early detection without nuisance alarms. Spacing rules differ for spot-type detectors vs. beam detectors and can be tightened based on environmental conditions.

Worked example(s)
Example: A long corridor may require detectors at intervals; corners, doorways, and supply diffusers can affect placement to reduce dead-air and avoid false alarms.