I had been working as a roadie plus a sound tech for one rock band or another for about 10 years, when I finally had my one brilliant system in life.
I used to do everything from setting up the lights to tuning the guitars plus checking the speaker levels. Then one evening the two of us were working for a Black Sabbath reunion show, plus at this point in life all of these men were really old. Have you seen Ozzy lately, he looks care about a mummy! Anyway, the men in the band got hot during their show, plus I saw one of the roadies drag a small out on the stage plus set it next to the drum kit. I realized that these stages could have hidden HVAC duct built into them, so the musicians could have air vents to keep them cool under the warm stage lights. That was it, my one brilliant system I ever had, so I had to make it count. I spent a few months working with my Uncle Mike, who taught me how to toil with sheet metal plus make HVAC ductwork. Once I had the skills I pitched my system to the band manager, who hired me on the spot to become the Heating plus A/C tech for the stage crew. I was respectfully loaned out to other bands so I could modify their stage setup to accommodate cooling systems. That was a few years ago, plus at this point pretty much everyone uses my idea, plus having built into the stage is something all major bands do.