Yes, the lengths and ratios vary. But that doesn't matter when you're balancing by the adventure, because you can balance it accross that spectrum, using the exact same metrics they use to balance encounters.
One fight or five or fifty, it doesn't matter. If that one fight is as tough as five, and each of those five fights is 1/5th of that one fight, then they're balanced with each other.
It is directly comprable to what 4e does quite well with solos, elites, and minions. Just over a different timescale with more variety in activities (thus making it easier to balance extreme effects).
If you can't be convinced by rational discussion, then you can't be convinced, and there's nothing for it. You seem like a thoughtful person, though, so I don't understand why you wouldn't be open-minded about this.