The key to encounter design is that an encounter (whether it involve combat, riddles, or some other task) has to be interesting to spend time on it. The reason the players will probably enjoy the task of obtaining the wolf's pelt is because it's both fairly broad (one possible option is to find a nearby village and just buy one and that would take seconds of ingame time, because it's not fairly interesting) and because it's inherently interesting. After all; the wolf's pelt is attached to the wolf, and the wolf has sharp teeth and a desire to not be seperated from its pelt, which turns the situation into a conflict.
(Conflict being the key word, because conflict is what makes the game interesting)
But the task of cutting down trees isn't a conflict. And as such, while it takes a lot of time, it isn't inherently interesting. This in turn means that players won't spend much time on it, and shouldn't spend much time on it, because it's a boring part of the campaign.
So the goal of the encounter design shouldn't neccesarily be that the task isn't trivial, but rather than performing the task should be interesting to the players. Introducing some form of conflict or complication will make players want to invest more time in figuring out and solving the problem.
I'm going to assume the crazy old hermit lives in the wilderniss and outside of civilization. Below is a list of possibilities to make the trivial and boring task of "cut wood for winter" more interesting.
- The hermit lives on top of a hard to traverse hill with a small bridge leading to his home. Cutting down the trees isn't an issue. Getting them to him, will be.
- The nearest wood is hours away. There are no tools available to transport the wood back all that distance, and there's no time to do it the hard way.
- Most of the trees in the local area struck by some kind of disease and would not burn. (or be dangerous when burned). Either the players need to fix the disease, or they need to figure out how to find healthy trees.
- The wood is protected by Elves/Druids/Treants/Whatever and they aren't really interested in having them cut down by random people. They'll need convincing in some way.
- The hermit doesn't actually have any woodcutting tools. Or a storage place. Or a fireplace. Why the hell does he want us to cut wood anyway? What is he up to?
You can try the same kinds of tricks for other tasks. The key is to make them interesting, by introducing complications that rule out the simple solutions. Think over the steps needed to complete a task ("find tree", "cut down tree", "drag tree back") and then add reasons why it isn't as simple as saying these things in a row to fix the problem ("there are no trees to be seen", "the tree has DR 20/adamantine", "it's heavy as hell") and then make the players figure out how to get around the problem. Try to introduce issues that make sense story-wise and the players will probably enjoy fixing them.
It doesn't have to neccesarily take effort on behalf of the players or their characters, but the key is to make the solution non-straightforward. This forces them to come up with a plan, which will increase game time needed.
The more game time you need, the more or bigger complications you will need to introduce in order to stretch things long enough. You can even start combining complications, for bigger issues. At some point, you can introduce so many complications that even a simple task like "cut some wood" can turn into an adventure in itself, although you must of course be careful that your players will not at some point tell the hermit to stick it where the sun don't shine and leave.