Don’t throw data away.
This is a software engineering principle that doesn’t help often, but when it does, it saves you big.
What do I mean?
Eg - You are building a social network.
A user is creating a post.
For that action, many types of data are required - post content, post time, user device, location, etc.
But suppose your app has no use for location information at this moment.
So you ignore that information and don’t save it in the database.
This will work great for the time being.
But in the future, if you need to create a feature to show a heat map of posts, then you need location data.
Then, you will be mad you didn’t store that data when you had the chance.
This is just an example but you will run into similar problems time and again as you develop software.
So, it’s a good idea to store all related data for an entity (here, a “social media post").
You don’t know when you will need something.