I generally on some bots can get a triple+ return value, even with only a few SBD put on. But I stopped for a few weeks when a lot were always putting on 15SBD +
But I am only using it now and then, withdrawing some out to secure savings and get things I need atm, but I still like to put some back into Steemit for curators etc.
A max bid of $5 or whatever would stop this behaviour and ultimately even out the playfield for everyone.
That would also allow many authors to increase the rewards a little bit, instead of just a handful on each bidding round. - But I guess that'll never happen.