I have been working with OutSystems for a few months now and I haven't found a neat way of breaking apart code. For instance, perhaps you need to do X, Y, and Z within a Preparation. There are no ways to refactor the portion of code you are working with. Rather than putting comments on the page to explain what you are doing, it would be nice to put all the blocks within a non widget Container. This Container would be highlighted a specific color and each color you specify can have a different function. Such as red being validation, blue being data related, green could be sending users to another page.
Screen actions are a little different. If you have a lot of code in one screen action, just make a new screen action for that big of code, this is not possible within a preparation. It would be nice to use this non widget container within a screen action as well.
This idea is similar to regions in .NET coding. You can make a region and collapse or expand it when coding. This is very similar. It's all for organization purposes to make sure that the code you have looks good and is easy to read.