I used to find putting an enhancer on the entire mix to be fatiguing, after a while... your ear gets used to it, and you are back to square one. My favorite use for it was inside a mix... pick the one thing that needs a bit more 'sparkle', and shade it in until it JUST pops a bit more.

I remember doing a lot of mixes in the 80's using drum machines, and a bit of Maximizer on just the snare and cymbals would help crisp it up nicely. And a dull acoustic with a bit of SM was a thing of beauty.

But I never liked it for the whole mix...