Research indicates that momentary time sampling (MTS) is often the best interval-measurement system when observing duration of behavior. Several recent studies recommended considering mean duration of target behavior, as well as durations of measurement intervals and observation sessions, to minimize measurement error in MTS. This report describes the steps we used to minimize measurement error in a single-case design research study. Further, we detail our methods for monitoring and reporting MTS measurement error across conditions by intermittently collecting and analyzing duration per occurrence measurements.