This is totally 2nd hand anecdote, but I've heard stories from several people who worked at MSFT (all 10 plus years ago, so maybe it's changed) who put in a handful of hours of work per week. Still got promoted. Spent most of their time doing what ever, things like playing World of Warcraft in a competitive guild full time.

In all cases, these people ended up leaving to go to highly demanding startups, because that's what they would rather have been doing. But the point is, even at large, high paying, very successful companies there are lots of niches where you can get away with doing very little.