The default window layout of Sandbox was designed to best utilize the available screen space and is usually a good choice for most standard situations.
However, don't forget that you can customize Sandbox completely to your needs and make it fit for the tasks you are currently working on. Depending on what you work on, the default Sandbox setup might not be your best choice.
For example, a window setup that is good for editing in-game cut scenes might not be optimal for AI setup tasks or working on confined interior locations.
For everyday work, it can make sense to create various Sandbox layouts and then switch between them depending on the task you are currently working on.