In Finland we have a rather nice concept called freedom to roam (jokamiehenoikeudet). It grants a big bunch of different rights that you can utilize while wandering in the nature. For example you can camp or pick berries or mushrooms (excluding backyards, gardens etc.) My next story is just about that: picking blueberries.
There are two main ways to pick the berries: by hand or with a berry-picking rake. Picking with a rake is by far faster than handpicking. But there are other aspects to consider. Blueberries are soft. The rake will break at least some of the berries. Also, they will be accompanied with a lot of extra leaves and other rubbish. That's why the method will require you to clean the berries.
From lean & quality point of view there are a few problems. First, you will need to have extra storage space. You need to keep the clean and dirty berries in different containers. And the batch size is really big. All the dirty and clean berries need their own space. Second, you will need to move the berries. In lean methodology this is considered waste. In reality, all the extra touching will also make the berries sticky from their own juice.
With handpicking you can pick straight to the final container. You don't need any extra space and there's no extra movement. This also means that the berries will stay in better shape. As a downside, your hands will get blue.
But as in any other things, you should think about your priorities. Largely it's quality versus time. If you are not in a hurry, I'd suggest handpicking. You will achieve a one piece flow. From the forest ground straight to a freezer ready form. But if you are trespassing on someone's backyard and want to get away fast, just use the rake a flee before someone will shoot you. You can then live to clean the berries at home. ;)
One should also note that this isn't as black and white with other berries. For example cowberries do not get as sticky even when you use a rake. And most of the time you don't get as many rubbish either. So there the quality is almost the same with both methods, rake is superior in speed.
Lean thinking is an interesting (and many times rewarding) thought experiment and can be applied also in ordinary life.