Its not my system but you have a set amount of sp per share. So if your upvoted from any pool the value would be the same.
The reason they put you in lower pools is to make sure you are getting a good persentage and not a dust vote.
In the higher pools you could drop below 1% and steemauto doesn't accept a persentage lower than that, so they put you in a lower pool. This brings your persentage back up again.
But if you start posting to the point that even @SBI6 is below 1% you will go into @SBI7 or @SBI8. In these pools you only get one upvote a day. This helps to keep those who post a ot from going below 1% upvote.
The main thing is what ever pool you are in your ROI is the same based on a weekly upvote value