A single deshedding session usually takes 15 to 30 minutes for most dogs, and can run closer to an hour or two for large, heavily double-coated breeds during peak shedding season.
The actual time depends more on coat density and how recently the dog was last brushed than on the dog’s size alone. A dog deshedded weekly typically takes less time per session, since there’s less built-up undercoat to remove. A dog that hasn’t been brushed in weeks will take longer simply because there’s more loose hair to work through.
There’s a second way to read this question, too: how long the shedding season itself lasts, separate from any single brushing session. Seasonal shedding typically runs two to three weeks from start to finish, though it can stretch longer depending on climate and how consistently the dog is brushed during that window. Falling behind on sessions during that stretch is usually what makes the whole season feel like it’s dragging on.
