Ehhhh, don't know about that. Depends on which heyday one is talking about.
Before the mid 1960's 120, 620 & 127 used to be the consumer films of choice - all those Kodak Brownies, Zeiss Box Tengors, Agfa Clacks, Rolleicords, Zeiss Nettars... A selling point of 6x9cm cameras was that you could get viable contact prints, getting enlargements 'back in the day' was expensive. 122 film used in older Kodak folders produced 3.25x5.5 inch contact prints. The era of contact prints from roll film faded when you could get 3x3 inch "Jumbo Prints" from 6x6cm negatives.
Consumers bought 35mm cameras to take color slides. Unfortunately nobody told consumers to edit their slides before showing them to their victims. Consumer habits re editing haven't changed much with copious quantities of cell phone images.
I don't think consumers ever took to 35mm B&W - it was the realm of press photographers and amatures with darkrooms. Heck, it took a long time for press photographers to shift from 4x5 to 120 - it was war photography that brought 35mm to press photography.