Time-sensitive network experiments are difficult. There are major challenges involved in generating high volumes of sufficiently realistic traffic. Additionally, accurately measuring system metrics is not trivial when highly precise timings are required. The majority of these problems arise because generic network software and hardware components do not provide high-precision timing guarantees. In this paper, we study the challenges associated with performing time-sensitive network experiments in a testbed, including generating realistic network traffic, emulating delay, approximating large topologies, and collecting high-resolution packet-level measurements. We provide guidelines for setting up testbeds, paying particular attention to factors that may affect the accuracy of experimental results, and we describe obstacles encountered during our own experiments. Many seemingly minor details can have significant influence on an experiment's results and, therefore, require careful a...