This must have been before my time, or at least before I could remember, but I've heard that in earlier times, when stake conference and general conference were held, sacrament meeting still happened. Does anyone know when this particular change was made? Did the switch happen during a gas shortage?

I'm in Northern California, 68 years old. We never had sacrament meetings on general conference or stake conference days.

Until the 70s, stake conference was in Oakland, with morning and afternoon sessions on Sunday. They also served a paid lunch in the gym or you could bring your own picnic lunch. Many of the families would go to Fenton's, an ice cream parlor after the last Sunday session.

I don't remember it ever being held on GC Sunday since there was an afternoon session of GC.

Stake conference used to be one session in the morning with SM in the afternoon at the usual time (at least in Utah). That ended when the split schedule was replaced with the block schedule.

I remember the same. Weber/Davis counties 60s and 70s

My memory on this goes back to about 1955 and from that time GC meant a holiday from any kind of ward Sunday meetings.