Sheryl, yes I sometimes still do a thin layer of pea gravel on the bottom of my pot (really its out of habit, no scientific reason!) My thinking is that when the roots get long enough to get down there, they'll have a bit of water to absorb
I don't know what is actually happening I just know that when I use perlite, the pot looks drier between watering and my plants seem to appreciate it too.
Just in the past month I've begun to use chicken grit (crushed granite) mixed in, regular potting soil, with perlite added - I don't really measure anything.
Totally notice a difference with the plants once this chicken grit has been used!! (I do mix it throughout the soil, on my indoor plants I haven't used it as a top dressing, only my sempervivums - which are outdoors)
Hope that clears up questions? More than anything, the huge shift happened when I stopped watering the indoor succulents! Even the little cuttings, I am very light on the water