It’s not a question of any one test so much as it is a question of potentially, which test fits me/you best?
As Chad points out in another thread (quoted above), there are other testing options, so it’s interesting to me to think about why one may choose one test over another. Sufferfest uses 4DP, Zwift seems to adhere to the traditional 8/20 tests, TR uses the ramp test. There are reasons that each brand uses their own testing protocol, but it doesn’t mean that all testing protocols are the same or would yield the same FTP estimates.
There is a goodness of fit here that to me is of interest. Measures of goodness of fit typically summarize the discrepancy between observed values and the values expected under the model in question. The generic advice is to “pick one and stick with it,” which is an option, but not necessarily the best option. If you choose a testing protocol that for whatever reason best matches your FTP and you stick with it, that would yield better results than just picking any one and sticking with it.