I think cleaning up old branches is a good idea, particularly ones that have been merged in, but of course sometimes people use these in a similar ways as tags (i.e. a fixed version that they wish to keep). I'm not sure if nesting actual branches inside another level fits well with standarad svn repos (which may complicate any future migration to git) but we could probably cope with this! I have tried to make branch names that clearly indicated the purpose (when I could remember) which hopefully...