It was the fact that all my campaigns were homebrew, with ever increasing levels of detail, that caused my wife to encourage me to submit material to Dragon way back when. All my early articles were based in my homebrew campaign of the Sovereign Kingdoms, where the name generator articles I wrote were standard for each race, the Charcoal Burners Guild was a psionic conspiracy, herbalism was an important part of a witch tradition, and several npc wizards were vying to create the most interesting spells.
My professional material is a good deal more removed from my homebrews nowadays, and the Sovereign Kingdoms are long since over (replaced by Halcyon, the Tiered City, the Middle Kingdoms, EverStar, and now Mutant Age), but a lot of my playtesting is taken out on my own players even today. And occasionally a home game concept sneaks into a book I do.