Do you chill Beaujolais Crus before serving?

This. Not just lack of central heating but older buildings (eg ones with cellars) often draughty. This started to change in the sixties.

By the same token, many whites often served too cold (eg ‘fridge temperature).

This.

During warmer months, I frequently place my decanter on a shipping foam ice block — that seems to keep the wine at the perfect service temperature. Occasionally, the wine will get a bit too cold — nothing a couple minutes in the glass won’t fix — so I’ll then just take the decanter off the chill paks.