More time does not equal better quality
When you start mixing for the first time the process may seem daunting. You have all these powerful plugins and effects at your disposal and you want to make use of every single one of them. You might focus on all the little details and soon you will be working on a mix for days or even months.
My first mixes certainly went this way. I believed that the more time I spend on a mix the better it could become. But oh man, I was so wrong! I now found a way of mixing that seems to work perfectly all the time.
Objectivity fades with time
What if I told you that the mixes I made in a couple of hours actually sounded better than mixes I was working on for days. Us humans can only stay objective while listening to a certain track for so long. If you spend a long time working on a song you seem to lose perspective of the big picture.
A layman doesn’t listen to a song thinking this snare needs more compression or this vocal needs more reverb. He may only think about the drums being too loud or the harshness of that guitar solo. If you start mixing a new song you also listen like this. You start by setting up a basic volume balance and removing harsh and muddy frequencies with eq. The longer you spend on a track the more you dive into details and the more you lose focus.
Limit yourself for better results
That is why it is so important to give yourself a limited amount of time to mix a song. If you give yourself 4 hours to mix, you only have time to focus on the most important aspects of the song. This is where all major improvements are made, nobody will notice that -0.4dB cut you made at 432Hz on the rack tom. Try to listen like everyone else who hears the song for the first time.
This way of working is hard in the beginning and it takes some time to get used to. But if you do this more often you will learn to mix more efficiently and get better results quicker.