I think it's "generally" true. I saw a mention of some where the transistor had 4 pins: Emitter, collector, base, and ground (can). Presumably for RF shielding

I think it's "generally" true. I saw a mention of some where the transistor had 4 pins: Emitter, collector, base, and ground (can). Presumably for RF shielding and they wanted a higher quality connection to the can without soldering/clamping it directly.