It's not about how much time you spend on the Steem blockchain, but how much value, quality and resources you put in, for example if your heavy investor on the Block chain you do not even need to spend much time to be able to earn more than 150 US Dollars, when you look at heavy investors like @exyle, it's not about time but their investment and Resources including influence and affluence.
The days when you need to constantly be on the blockchain and spend a lot of time to actually make money is over, these days it's about be More involved with the real deal, for example if I have 500,000 steem power, I could support a lot of big users who would in turn support me back. So when I write a post I could basically the earning 100 steem on one post and not even break a sweat. And I will do this better than anyone who isn't invested on the blockchain or have people who are willing to support him or her.
It all boils down to business so like I told you earlier it is no longer about time. However you can earn more than that on the Block chain but it all depends on the fact is I have stated above and not factor of time. At least not anymore. You can test this theory by just investing on Steem and you'd see the difference. However if you have somebody who is lucky enough to put you on automatic votes of let's say a $5 or $10 a day then it'll be achievable.