+4 ... +8 ... ??

Sorry but that is a ill informed reply.
No you should not aim for your levels to be “at” 0dBfs. Not ever while working.
If you want to push your master that way, be my guest, but never risk distorting precious source material by overloading signals.

That 0db crappolino is some old remains from backin the days with 16bit recordings and bad converters.