I may be missing some context, but I think OP's point was if you have a task that requires 100% human intervention, and you automate 30% of that, its potentially a very big positive. What % is a good number depends completely on the context -- 10% may be best-in-class and drive you to profitability, or it may be 100% or bust. Personally, I was unable to discern the context from the article.

I don't know. My microwave is only good for about 20% of the cooking I do, but I still use it.

If you only eat Hot Pockets, your microwave will handle 100% of the cooking.