Sure you can do if you're really sure that you won't need to group by something else later. You wouldn't want to store more granularity than necessary but you can't go back in time to get a data point you didn't store.
What I am doing with one program could almost be called a data lake because it is just a bunch of JSONL files that have really varied data in them. But it's organized by date and hour per day as well as predefined keys, since I know I will need to query it that way.