Interferometric SAR (InSAR) has been used extensively to measure vertical land motion (VLM) resulting from both natural and anthropogenic causes. Careful processing is required to produce VLM estimates with mm level precision and the processing choices have an impact on the accuracy of the resulting estimates. In this comment on a paper published in EO, the authors discuss some of those choices and their impact and, in particular, best practices for validating the accuracy of products and benchmarking. These are important issues for the whole community working on VLM using InSAR to consider and to adopt best practice.