In recent times I’ve seen a take more frequently that boosting polls far away from the elections just helps the populists. German article:

https://www.spiegel.de/wissenschaft/mensch/sonntagsfrage-die-staendigen-scheinwahlen-schaden-der-demokratie-und-gefaehrden-sinnvolle-politik-a-cdc827a3-0160-467c-8bdd-a6e009da4b50

English paper (not peer-reviewed): https://www.wiwi.uni-muenster.de/loep/en/research/publications/154536

Or greedy.

For a nighttrain that’s less bad than for a regular train i’d say.

My guess would be Freiburg and/or maybe Karlsruhe.