Thanks for your responses and info!All of that, for better or worse.
I've been playing this game since I started a couple years ago, and it's a big part of why I have pretty much nothing to show for all my efforts in bonsai.
I tried potting some aloe vera in pure sand - very fine stuff mind you - and it stayed too wet and compact. Heavier grit compacts less, and holds less moisture, but little room for root movement. I've tried about everything to mix in compost, but keep coming up against the too-wet-too-long issue, especially since my kids like to water the plants when I'm not looking.
I am convinced there's a way to allow all the positive aspects we need in soil, but not have to water multiple times a day in summer. Just haven't found it yet.
There has to be, otherwise I might have to quit until I'm too old to go camping.
One last question - what about agricultural charcoal, around 1/4"?