The thing is when your application is under "Review Required" this indirectly means that your files is thrown on some table for months until one officer later comes and finalized it. At that time, 8 months will be passed and your stuck in mud without knowing whether he will accept or reject your file.
so preferably (my opinion) get GCMS notes.
Know where your weak spots (grey areas), if you can address it then send additional supp documents. If not, then either withdraw the app and submit a rectified file or just wait for ever i guess.