A server system with one or more processors and memory receives respective client environment data from a first client device of a plurality of client devices, where the respective client environment data is provided to the server system according to predetermined collection parameters. The server system determines characteristic criteria for identifying potential target clients for additional data collection based on the respective client environment data received from the first client device. The server system sends a data collection command to at least one second client device of the plurality of client devices in accordance with the characteristic criteria.