I always keep my camera off unless it's a handful of situations, like meeting someone for the first time, or making a big presentation and introducing myself. Turning the camera on is more the rare thing.
On technical calls with two or three people where we all know each other we rarely turn the cameras on. For big meetings, the bosses prefer to have cameras on the whole time, but at least require that we start meetings that way, then we can turn them off after the meeting really gets going.
