One layoutfile per Screen resp. per panel. I usually use CLV (one layout) and Panels for the content (one layout for each different layout for the panel used in CLV).
I do not like all on one like in the pic above
But at the end it is up to you and what you are more familar with.
I fully agree with DonManfred!
How do you manage the views in Activity_Resume?
For me, it's not a good solution. You should manage the views in the DesignerScripts.
I suppose you are using only one Activity, even thoug I would use different layout files, one for each 'screen' panel, they are much easier to maintain.
1. You lose all kinds of features such as anchors, auto scale all (will not work properly) and designer script will be more complicated to manage.
2. Why load all the views when the program starts? Will be faster to load the currently required layout and load more as needed.
3. You can have any number of layout files. I think that it will be easier to manage smaller layouts. It will also be more flexible.