Rofel Wodring
Explorer
My feeling from the two campaigns I'm involved with, in conjunction with the values used in the adventuring day XP table, is that four encounters per day is (or should be) typical.
If a DM is allowing a single-encounter work-day they're distorting the game balance. That is fine for their campaign: I am not making any argument about one-encounter adventuring days.
Take it up with the game designers. I played through Storm King's Thunder, Tales of the Yawning Portal, a bunch of DDAL one-shots, and am now doing Tomb of Annihilation and they frequently set up plot and even dungeon progression so that there's only one or two challenging encounters for the whole dealyo.