I'm also not primarily a game designer. I dabble.
Despite that, I get a ton of use out of this simple tool.
For example: wandering monster tables, or random encounter tables if you prefer.
1. The "plateau" for rolling 9-11. Put a monster at 9-11 and you'll see it 30% of the time. That's often enough that this monster defines that table, and by extension themes the region, terrain, locale, etc.
Or time-traveling liches. (No, autocorrect, NOT "lunches.") Or mirror-universe versions of the PCs.
Won't happen often, fun when it does.
Alternately, want a second defining monster? Put it on both of those sets of outcomes for a 32% chance.
Assuming you have an oddball at either end, a defining monster at 9-11, and two monsters at 7-8 and 12-13, that's 5 monsters.
Even if you do 1/outcome for the rest, that's only 8 more. Combine a couple slots and you need even fewer.
Seeing the distribution on AnyDice makes this stuff easy to think about and gives you a clear path for making meaningful choices.