Why Walruses were limited as gunnery spotters

Why were Walrus aircraft not used more regularly for gunnery spotting?

They were used when practical, but slow spotters were vulnerable wherever enemy fighters or carriers could contest the air.

Forward observers often performed the Normandy spotting task, while a Walrus over the Mediterranean or near enemy carriers risked interception. The aircraft's usefulness therefore depended on local air control. A slow shipborne seaplane could provide valuable observation only where enemy fighters could not readily reach it. The operational limit was survivability over a contested fleet, not a failure to understand the value of aerial spotting.