I am using one or two layouts and find the concept generally Ok. However I would like to suggest the following. Under L3 in Options, there was the ability to set the default action for loading a workspace. I liked the ability to reload the last workspace and so continue on with my study where I left off. In L4 if I choose to open a previously saved (Left Side)layout it opens with the contents as and when it was defined. for example, if I read through several chapters, and then close L4 for the night, when I open the same layout next time it reverts to the contents that were originally displayed. Now I know that I can go and rename the latest snapshot to the name of my preferred layout but this requires me to a) remember which layout out I'm using and b) actually remember to update the layout before exiting.
In relation to point a) above can I also suggest that it would be of great benefit to have the currently open layout name displayed on the application window next to the layout tab? Opening the layouts and trying to discern which one you have open based on a thumbnail is less than satisfactory.