Yes, that was the actual situation then. OTOH most mates in those days called up the sparks to help them out. A navy ship often signaled much too fast, they had no idea about the signaling level of the average merchant mariner. We signaled then SLOWER PSE.
The Aldis lamp was usually equipped with a mechanism which moved the large round mirror up and down when signaling. With a little bit rough weather it was hard to keep the light bundle steady and focused on the other ship. Because of the heavy mirror it was also heavy on the finger. An improvement was the kind where a rather small, black metal screen around the bulb was moving back and forth. Much lighter and therefore faster.
The Navy uses this kind of signaling lamp with professionally trained personnel.