Astrophysical jets have been detected in objects as diverse as protostellar objects and supermassive black holes, yet we still have not answered the key question of what system properties are necessary to launch a jet. This talk described multi-wavelength time-domain studies to determine if two classes of objects at opposite ends of the energy scale are launching jets. First, Cataclysmic Variables (binaries with mass accretion rates of <= 10-8 M☉y-1) were previously thought not to launch jets, and have been used to constrain jet launching models. Nevertheless, recent radio observations have indicated a jet in one system, and have shown that that system is not unique. As regards the other end of the energy scale, we still do not know if the most powerful stellar explosions (Super-Luminous Supernovæ) launch jets. Recent improvements in sensitivity (particularly at radio wavelengths), higher-cadence transient surveys, significantly improved telescope response times and longer-term monitoring have led to substantial advances in these fields. The talk discussed how we are using multi-wavelength studies (with different cadences and coverage times) of these two extremely different classes of object to determine if they launch jets, thereby to constrain the properties necessary to do so.