There is allways a need of testing some part of your code. So, you can group some parts to test alone. This is also a reason for having some code separated. If you think some code is not going to stay like it is for a long time, by having it at a subrutine, you ensure that everything that is related to it goes modified even if you forget what was all about.
The correct way of structuring some code, IMHO, is by starting keeping as much as you can together.
Then with the use, you are going to notice the risk of keeping all in this way, and you are going to happily start cutting some code and making some standarization for future improvement. | 