Once performance has a place in museums as a mode of exhibition, it problematizes its relationship to the event, and shifts its reception thresholds and expectations. This article offers an analysis of a number of durational exhibition formats based on the experience of temporality they offer, so as to examine how a system of temporal regimes comes into play. These projects have a duration that is dictated by the opening hours of the museum. The focus will be on the implications of this openness for the production of other modalities of spectatorship, and on the reconfiguration of institutional praxis.