First & foremost, thank you for the compliment.
And now to more important matter at hand, from the experiment that I carried out so far, I noticed 3 things that could help to boost the ROI.
Hitting the trending page really help. If you can stay there for 2 to 3 days, it is even better. On my previous experiment, I was in trending page for at least 2 days. So, That really helped. I am not sure, how this post will play out, we will wait & see, but it doesn't look good, it was in trending page for less than half a day. And it was no where near the top. Can't compete with the likes of all these:
Try not to get flagged by someone with a lot of Steem Power. I don't know how to do this, I mean if someone doesn't like another & he/she wants to do something bad to the other person & it's within his/her power to do so, then, what can you do...
When I did my previous experiment, I posted it at the time when the US is sleeping & the bidbots were not very busy, so I managed to get good ROI from the bots.
Oh and there's one more thing I noticed, the choice of tag is important: choose tags that are not so competitive. I am doing poorly with the tags here because tag like steemit is where the experts are - not suitable for beginners like me.
And finally, in summary, the amount required to hit the trending page is not fixed. It depends on who is already there but it helps to choose a less competitive tag and a timing when most people who use this platform are asleep.
Good luck. :D