Which Half Works?

I'm a quote person. I design and sell thinking/inspirational/funny quotes for classrooms. I get a daily quote in my email. Quotes make me think. One of my favorites is about advertising, by John Wanamaker: "I know half the money I spend on advertising is wasted, but I can never find out which half." It might be a bit tongue in cheek, but he's right: everything a marketing strategist creates and everything a business owner spends money on may not sell something.It's funny and sarcastic. The product might be bad, or the advertising didn't work as intended. Eh, so much for business and consumers - now I've analyzed this quote into parenting. What if only half of what I do sticks? I'm not concerned about wasting my time, I'm worried about messing up this important job. It just that they mean everything and I know that I'll screw up. Some days it overwhelms me, and that maybe only some of it will stick.

Nerve-wracking, really.