This paper examines the interaction effect between time (successive elections) and district magnitude on three dependent variables: disproportionality, the number of participating parties indicating strategic elite behaviour and the effective number of electoral district parties representing strategic voter behaviour. It is assumed that when implementing a new electoral system both voters and party elites must learn by experience the working of the electoral system over time to behave more strategically. If the hypothesis holds, this also implies that the effects of the electoral system should vary over time. Our hypotheses are tested by using multilevel models. The analysis is carried out at district level and two country cases (Spain and Portugal) are selected. The analysis reveals an independent time-effect on all three dependent variables. However, strategic learning as a result of mechanical effects of the electoral system at the district level seems to be absent.