Does your home have working windows and are they double hung sash windows? The intent was the bottom sash would be opened on the cool side of the house and the upper sash on the hot side. This would create an airflow of cooler air entering and warmer air exiting. Well placed fans would help create airflow.
But you’re right, people also used them for the hottest nights too.
Yeah, the layout of the house and lots of huge, openable windows could get you pretty far in terms of keeping it comfortable (most modern houses cannot do that, and are horrible even in moderate temps without AC) but if the breeze was weak and temps got past 90F nothing would help much. You could run a window AC non-stop all night and keep it close to 80, maybe, but that was still too uncomfortable to make it worth the insane electric bill that would follow (no insulation, original single-pane windows, no modern mostly-airtight envelope in the walls—I do mean the AC unit would run all night). Without that option we’d probably have had more like 5-6 patio-sleeping weeks per year, instead of 1-2.
But you’re right, people also used them for the hottest nights too.