You see, I made my calculations assuming that you spend 3 seconds per ad. If you say it can take five times longer(with which I absolutely agree), it means that even with 5 accounts you'll get the same time needed for completing the task, 42 hours.
Yes, "even with 5 accounts" it would take 42 hours, how about 15 accounts? How about 15 different places? How about 15 accounts on 15 different places? You realize these people are literally making a living out of this so they would have figured out a way to make it as quick as possible right?
I mean you are probably a lot well off than these people so I am pretty sure you are not really in a rush to figure out how to make the most amount of money from these places, but between VPN and ToR browsers and managing different IP's and having multiple cheap smart phones that could be used to having many accounts in many different places, that 42 hours could be cut down to as little as 5 hours if they really work for it, mathematically it is there to see.