As you’ve found, Picard is really not great with exceptions. In situations like that, your options are either going to be doing what you did (every time you work with that release), or tweaking your naming script in such a way that it is able to do what you want automatically – and because most of us use Picard for batch editing, I wouldn’t hold my breath for that choice changing.
What I have done, though, is write my script to recognize custom fields like
%albumfolder%, so if I do want to make an exception for something, I can add a new entry in the bottom pane with the value I want, and it will be saved into the files themselves as well as being part of the path/name. That way, Picard is able to see that I did indeed mean to put it somewhere other than where the rest of the tags would have it, and it will “remember” that every time I load that file in the future as well.
The other solution I’ve heard mentioned would be to support multiple profiles to easily switch between options for classical and pop music, say, but that feature’s not currently implemented and I’m not sure how much traction it’s gotten. Besides, it can already be emulated in scripts by wrapping them in a check for an
%is_classical% flag (manually set or from Classical Extras), so there’s not as much impetus to add it.