On steep alluvial fans, debris floods happen rarely but are often catastrophic. Debris floods and their associated hazards are well documented, but the time between flood events has generally been considered a period of ‘dormancy’, and thus ignored. Here, we present results from a series of four alluvial fan experiments in which we examine the inter-flood period processes and their influence at both event and fan evolution timescales. We built each fan from the same number of debris floods, and the same volume of sediment, but varied the duration of the inter-flood period. This duration had a fundamental influence on fan morphology: in particular fan slope and fan area varied between the experiments. In addition, longer inter-flood periods led to increased flow channelization and channel incision near the fan apex. Our findings challenge the notion that inter-flood periods on steep alluvial fans may be considered dormant. Moreover, the results suggest that longer inter-flood periods may act to contain subsequent debris flood events, shift the locus of debris flood hazard, and reduce their severity.