"If you regularly use a high-quality gasoline such as Chevron, you probably don't need Techron® Concentrate."
That tells me that constant tiny amounts are indeed helpful.
If you don't use their gas and want to add Techron to other gas, they say this... (warning: math ahead!)
"Use every 5,000 kms to keep your entire fuel system clean.
Available in two sizes, 355ml bottle treats up to 45L and 590ml bottle treats larger tanks, up to 75L."
Virginoil has a 45 L tank so we'll dump in 355 ml every 5k km (3k miles). Say you get 20 mpg. That's 150 gallons, 600 L of gas in that time. If you added that bottle of Techron gradually over the whole time, that's just over 0.5 ml Techron per liter gas, so 22.5 ml per 45 L gas. So an ounce per tankful sounds just about right.