We can set out with good intentions, but sometimes, the tracks we end up with after recording are “hotter” than we want. Perhaps that spontaneous performance wasn’t at a technically correct level, but capturing the feel of it again would be nigh on impossible. Or perhaps, more prosaically, you’re mixing a track someone else has recorded and you need to pull the levels back to a point where the sum of the parts doesn’t light the clip light before you’ve started to mix, (not, of course, that any of your mixes would ever do such a thing!). Setting a good gain structure at the start of your mix can go a good long way to ensuring that you don’t face an uphill struggle by the end and, one way or another, your DAW has everything you need to make that easy for you.