Embodiments of systems and methods that can facilitate data collection for valve diagnostics. The systems can include a valve assembly with a valve and a sampling device that is configured to access a repository with a first buffer and a second buffer. During operation, the valve assembly is configured to read data representing operating variables for the valve into the first buffer. The valve assembly is also configure to determine a quality measure for a first sample set of data from the first buffer, the quality measure indicating the usefulness of the first sample set of data for predicting performance of the valve relative to a second sample set of data from the second buffer. In one embodiment, the valve assembly is further configured to read data from the first buffer into the second buffer in response to the quality measure indicating that the first sample set of data is relatively more useful than the second sample set of data.