I add a 20oz bottle of the Techron to a full tank of gas in my wife's 2009 Cayenne just before every oil change is due. I've done this for many years.
Try to use nearly all of that tank of gas before you change you refill with gas. Then change you oil. If you look at the color of your oil before you've added the Techron fuel system cleaner, and after that tank of gas has run through your vehicle, check the dipstick and you'll see your oil is substantially blacker. So, its cleaning out something in only 400 miles.
For more than 10 years, I've also added Techron to my Porsche 1999 C4 before every oil change at 5K miles (it's my daily driver so I do 2 or 3 oil changes a year).
Techron won't hurt the vehicle, and does significantly improve how it runs, especially if you've not used it before. But always add it, and let it run through, just before your oil change (not after, or mid way through an oil change cycle).