Another thing to keep in mind is that the rules state that the 3 hours is only for "coding, making sound effects/music, art, and other assets. Writing a design doc, coming up with ideas, compiling your game, or making the itch.io page for it does not!"
Based on this, things that I have not counted as part of my 3 hours before are:
- Watching YouTube videos to learn new technology (recently been getting in to Shader Graph on Unity)
- Creating a prototype using that new technology while watching videos
- Messing about with different ideas in my prototype, e.g. shader settings, or particle effect settings
- Brainstorming with team mates on Discord, including creating sketches in MS Paint or with paper and pencil
- Writing a design doc - Sketching out level designs on a piece of paper
With my prototype I typically end up with some kind of horrible spaghetti code which I then discard. However, a prototype allows me to solidify the nebulous ideas I have, meaning that when I get started with my 3 hours I know exactly what I'm going to make.
I also completely agree with I_AM_STUPID above that I don't often get lots of free time at weekends, so having a limit of a few hours is really helpful. I've done a couple of jams that were all weekend before (e.g. Mini Jame Gam #41) which can be fun, but equally my wife and kids tend to get significantly less attention when I do that...