Hi, Marshal. Welcome. This technique is very common. I don’t like to say “On the majority of songs”. It’s just something I may do when the material might benefit.
It doesn’t have to be a limiter. It can be the high frequency band of a three or multi band compressor. The principle is simple as you outlined: a subtle high frequency boost can open up the sound during soft and medium level passages, but can sound harsh on peaks. So if you soften the high frequency peaks you may be able to have your cake and eat it, too.
Just don’t overdo it. It’s very tempting 🙂
I have the wonderful Maselec MPL-2 but ironically I haven’t used its HF limiter very much because for this type of functionality, softening to reduce harshness, I find the high band of a more gentle 3 band Compressor to work better for me.
And when it works great for you, you may get that pleasureful feedback from your client: “I don’t know how you did it, Bob. You made it both warm and clear at the same time!”
You asked for “settings”. As A VERY GENERAL GUIDE” I would say with a gentle 3 band compressor, something above 5 to 8 kHz and on loud passages no more than maybe 1 dB GR or the process will call attention to itself.
I used to use the Weiss DS-1 for this function. I had three of them. And so I could use one of them dedicated to this function. Today the softube Weiss can do a nice job. These days the Maselec MLA-4 does a nice job for me. The speed of the MPL-2 is so fast it’s more for softening quick high frequency instruments like cymbal hits or tambourines than for more sustained sounds.
That’s it in a nutshell.