Legislators are political actors whose main goal is to get re-elected. They use their legislative repertoire to help them to cater to the interests of their principals. In this paper, we argue that we need to move beyond treating electoral systems as monolithic entities, as if all legislators operating under the same set of macro-rules shared the same set of incentives. Rather, we need to account for within-system variation, namely, candidate selection rules and individual electoral vulnerability. Using a most different systems design, we turn to Germany, Ireland, and Portugal to leverage both cross-system and within-system variation. We use an original dataset of 345.000 parliamentary questions. Findings show that candidate selection rules blur canonical electoral system boundaries. Electoral vulnerability has a similar effect in closed-list and mixed-systems, but not in preferential voting settings.