I will always use GPS. Also, I will always use a password manager. And a calendar. And a note-taking app.
Why? Because our minds have finite space.
Data in the Mind
Our minds have intricate networks of neurons that allow us to remember things. But I can guarantee that you don't remember what you ate for dinner two weeks ago. And you shouldn't. If you do, you're doing something very wrong.
When we create new memories and learn new subjects, we are tweaking our current network of neurons to "make space" for this new data. The pathways that get affected could be very valuable in representing knowledge about a specific topic.
The knowledge that uses these pathways to represent itself isn't gone, but you make it harder to access because the amount of connections that can activate this area of the brain has decreased.
We don't decrease loss
However, if you "write over" this area enough and the representations get skewed too much, you could end up losing the ability to remember the information altogether.
Neural networks are beautiful because they fight this disappearance in the face of new data.
Neural networks are designed such that they score their ability to remember everything they've been taught and then try to find the best way to add new data to the network without disrupting the current neural connections too much.
This is in the form of a loss function which they are built to decrease. But we don't have loss functions controlling our memory. Ebbinghaus' forgetting curve shows that the percentage of information we can remember drastically decreases over time. After about a week, you'll forget at least 80% of the information you were taught.
So, if you want to remember something valuable, you need to review it. But also don't write over it with useless data, like directions to a restaurant. Leave that to machines.
Best Practices
Throw away learning anything that can be easily replaced by a tool or anything that isn't valuable enough to weaken the current pathways you've built up. Avoid repetitive tasks that will build up in your muscle memory without any benefit.
Why even attempt to remember what you ate for dinner two weeks ago? The act of doing so will strengthen the pathways that represent the memory, and you will be better at retrieving a useless factoid. Congrats!