Many domains involve gathering evidence, from forensic investigations and medical diagnosis, to everyday life. Howshould one order this collection, given the costs involved (e.g. time, financial, information)? Scheduling theory offersoptimal solutions, but requires clear metrics. Evidence can have many influences on it, which affect prioritization, e.g.degradation, contamination, etc. However, to date there has been no clear way to bring this into a unified metric, andthus optimal scheduling has remained out of reach. We propose a new information-based measure, KL, as a way ofencapsulating these information costs, and present maximum KL preservation as a clear rule & metric for scheduling. Wego on to test several heuristic rules for scheduling evidence collection, based on optimally derived algorithms, providingnovel formal backing for a dominant heuristic strategy for scheduling information gathering.