The new features of the global.xml are created in the « NewFeatures » section.
It works well if you do nothing, but updates after updates, this section can contain lot of features mixed together making it not easy to read.

You can move these new features in the appropriate sections to make clearer (I note the recommended section at the end of each new lines).
(Note that you can create your own sections if you want)

For the Characteristics.xml the new features are automatically created for each zombie section but all with same default value.

To easily keep global.xml clean and Characteristics.xml with last tweaks you can delete (or rename) these files, they will be automatically recreated the next time you press numpad 4 in game or the server restart.
Of course this last tips is useful if you didn't modified the default value too much or it will not save you so much time.