It makes absolutely no difference, it's all a relative perspective. Having your loudest element at unity means that none of the other faders will even approach unity. THat's how I mix as it gives me an instant relative peak level of all other mixer channels simply by glancing them. -3dB on a channel means that it's half the volume of my loudest element (nearly always my kickdrum), it's as simple as that. Nothing else approaches unity. Of course, this means that the master bus will clip unless I pull down the fader but that's absolutely no sweat and has no impact on my mixing workflow. Going back and forth wasting time adjusting all faders when one reaches unity or when the master clips is extremely inefficient and not grounded in reason.
RMS yes, but for some one new to mixing it isn't a good idea to whack all your faders up to maximum only to use a master to pull the volume down. That's just bad mixing etiquette it leaves you with little room for automation, and encourages new people to go OTT on processing.
There's always reasons for pushing up faders. There's also always reasons for pushing down faders. I hear this "don't touch the faders" myth a lot on the internet but there is absolutely no basis for it. If someone doesn't understand gain staging then not touching faders isn't going to help them.
There's no need for you to keep pushing faders up to hear your music louder, just turn your speakers up, (unless you've not recorded x-instrument properly with a good gain setting) then when you get to mastering you'll get the volume back.
When stuff starts distorting badly from having too much gain, from EQ boosting, compression make up or gain boosting, you can still hear it even if you're not going over 0db on the master. If it's the odd minor clip then yeah, not too much of a problem. Anyway, my 2p.
This has nothing to do with faders. Plugins can clip a mixer channel, but the channel itself will not clip, i.e. you will not hear any clipping artefacts. Going to great amounts of effort to achieve something that can be achieved simply by pulling down the master fader is not a good use of time. Everyone has their own mixing style and that's absolutely fine, but propagating myths about master fader = bad is not helpful.