- broad phase - when i do general learning on many different thing
- narrow phase - when i focus on my own code testing and experimenting

What you're talking about is

- research

- and development

Often called "R&D." Actually, "experimenting" (which you included in your "narrow phase") is part of "research."

Every project inevitably involves some research, whether or not it precedes development (it may precede a particular task in the development process).

Many people use an iterative process that includes "experimenting" as you describe.

Hi,

"Research is the intellectual backbone of game development...," found in my signature below here. Research goes through phases, but in my opinion it should be according to needs and purposes for the most part. In other words, it should mostly be tied directly to what you need to learn for your current and near future game development processes. I will even go so far as to say that as you gain experience, then it will also be tied to both your source control and your version control systems in the form of documentation, especially that which relates to the coding at hand.

What I am writing here is for anybody intending to have long term success in game development with the most efficient progress, but people who only do this as a hobby should focus on the things that bring them pleasure. Documentation is important for both philosophies of professional and hobbyist, however it is critical for professionals in regard to research that research documentation be directly connected in the development software to the coding. This serves many purposes as you can probably already imagine. A major benefit to documenting your research is that it holds you more accountable to not wander too much in your research, since you will tend to always be reminded everyday of the ultimate objective of your research, thus not "waste any time" with bunny trails. Some wandering is going to happen naturally because curiosity is too powerful to prevent all of the time, yet I believe that some benefit of learning for the future is to be had with it.

The more needs that you have in game development, then the more that you will see the logic of what I wrote here.