This video (there's a series of them but the first one is sufficient at first) was what helped me get started with obsidian.
I find it extremely useful for writing everything down and being able to easily access my thoughts and important information.
I also use the calendar plug in and daily notes. Every day I open a daily note and use it for my to do lists and to note down anything important that happened that day.
Obsidian is wonderful. I have folders with daily or weekly notes (and could do monthly or yearly too) similar to what you said. There are so many other features that I could use but haven't yet, because I got it working exactly how I need right now.
One example I use besides journaling is taking notes on YouTube videos. For example, with interviews of YouTubers who give a lot of advice. I can put them all in a folder and/or apply a tag to find them in the same place later.