I'm a little confused about when I should be placing plugin files into mu-plugins. I know it's Must-Use plugins and I know that they are automatically enabled.
In the network setting, though, does this force the plugin file to be enabled in all child blogs? Makes sense that it would, so is that the only time I should put a plugin file THERE in a network? When I want the plugin code to be run in each child blog?
For example, if I wanted to automatically set a new thumbnail size, should I do this there?
Or are there other examples.
And what about network activate?