Originally Posted by
speed.skater
It's not surprising. Every travel hacking intro I know will tell you to try not just 1x/4x, but also 3x (the case of the OP) and 1x. 2x seem to be suggested less frequently.
And, for the OP's question: I think in Europe, it's fairly safe to do hidden-city ticketing. Stipulations by the airlines that prohibit it may actually be legally void.
Unless it involves LH which recently sued a passenger for the fraud. While it has temporarily lost for apparently having filed in the wrong court, I would not be quite so quick as to make generalizations regarding regions such as "Europe". I am not suggesting that OP's mystery carriers will sue him, simply that broad generalizations are not useful for individual circumstances.