For someone who wants to hike to a lake and spend a few days fishing, then hiking back out, I suppose pancake mix might be a pretty decent idea. In that sort of a scenario your morning hours are spent near the lake so you can fish, and your breakfast can be padded out with pancakes, either more or fewer, depending on your luck with a rod and reel. You'll already be taking a fry pan for the fish. Afternoons you can snooze or poke around the vicinity, then come back to camp.

If your trip is mostly hiking, not fishing, the advice you've received already is spot on. Pancakes take time to make. They require a fry pan, which might be heavy. They don't adapt well to cooking on a stove, but starting a fire in the morning and waiting for coals, then doing clean up after, will waste most of the morning. You'll end up hiking in the hotter, dustier part of the day. In that scenario, cereal makes great sense. I take granola and dry milk, then add water.