My workaround (which wouldn’t be practical for everybody) is to “save as” my current workspace and overwrite the old one, so when I open an old file, it’s opening the old name, but it is now the current layout I use. It works especially well for my situation, which involves updating a whole series of projects. It is only a few seconds, but it is absolutely annoying to watch everything across three monitors change when opening an old file within the same instance of AE.