I once read that if your competition wasnt bidding on the smaller engines it was a good idea to bid on them, take the profits and reinvest them on the big engines again to have an edge.
or slightly different: Bid on the smaller engines, too (in competitive markets) so you dont give your competitors that possible edge.
What I do not understand, at all, though:
Its great to make a profit from engines if they are less competitive (even if they have a very very small market share). But how does reinvesting them help give you an edge over the competition on the other engines?