My grandparents (born around the 30s) never described it as a common thing here in the north. I can't vouch for previous periods, but siesta mostly makes sense for outdoors jobs in hot climates (where it's actually a great idea), so I would assume it was never common in the north as the climate is much cooler.

In the south, it's also becoming less common with the change from rural to urban living and from outdoors to office jobs.