This topic is not clear.
Hitting 0db with any element of the track is very very bad in a mixdown, unless you use clipping for voluntary arsh digital distorcion (which any sound engineer would lovely recommend you to dont do).
Only moment when you are allowed to clip or get to 0db is after the limiter during the mastering.
I recommend you to use the "DR offline meter" to analise your bounce and check how your mixdown's dynamic range and peak and RMS are hitting before mastering.
It will give you an help on understanding mathematically your processing.
Also a spectrograph it's essential where brain cognition cannot get a wrong mix side of a tune.
All of that, doesn't substitute your ears.
A perfect mixdown it's done just using your ear taste and following basic rules.
You gotta pass thru the mastering. Which mean, other machines with physical limits will get involved after mixing down.
Never clip before get to the eq and compressor of the mastering chain.
Allow-6db headroom when mixing down, that to keep a good dynamic range and help the mastering compressor to work properly on its fine work.
After that, anything else on your taste, you can do it!
