The interaction-driven supernovae Type IIn are (in)famous for the wide range of light curve properties they exhibit. Here, iPTF13z, a SN IIn with a durable and peculiar light curve, will be discussed. The light curve of iPTF13z exhibited at least 5 re-brightenings ("bumps") and evolved slowly during its observed 1000 d decline. SN IIn light curve bumps are rare (cf. SN 2006jd) and we interpret the iPTF13z bumps as being caused by SN ejecta encountering denser layers of circumstellar medium (CSM). The structured CSM indicated by the bumps of iPTF13z suggests pronounced changes in precursor mass loss rate. A precursor outburst was identified in archival data from around 200 days before the discovery of iPTF13z, strengthening the interpretation that the progenitor star was restless in its final years. The combination of a precursor outburst and a bumpy light curve makes comparisons to SN 2009ip relevant. We will also discuss the problem of whether iPTF13z was driven by a destructive explosion of a star, or a violent but non-destructive eruption. The un-targeted Palomar Transient Factory (PTF) survey and its successor, the intermediate PTF (iPTF), found and spectroscopically classified over 100 SNe IIn during the period 2009-2017. A sample of SNe IIn from (i)PTF, having optical photometry and spectroscopy, is further studied to explore the properties of SN IIn light curves. Some preliminary impressions from this study will also be discussed.