I even tried this and got different results.
I made some very small bets at some sports betting site, sent the money with recommended fee.
After that, when I won something, it sent me the total amount (small enough) with the least fee like in between ~600-800 satoshis, but it got confirmed in the next block only and it was also holding "High Priority" instead of medium.
So, even I cannot understand how exactly does this thing work.
I do not exactly undertand,But I have read that priority is given to the highest fees.
But i do not know if it is relative highest fees or real highest fees.
I do not know if the transfer is selected among all transactions oronly among a group of transfers.
I have noticed on a ponzi where one needs 1 comfirmation that often 2 or 3 transactions are comfirmed almost the same moment.