Good question. I don't know if we should, although I've heard similar things said about requests to non-FISA judges, as well. It makes sense to me that if investigators' careers involve learning to cross their t's and dot their i's before they go to a judge requesting an intercept, and they spend years doing it, they get good at it.
Separately from belief, which is somewhat subjective (i.e. it involves more inputs than is practical to list in a discussion), it's important to realize that on a logical level, there are at least two interpretations to a 99% acceptance rate: (1) the bar is really low and (2) there are pre-filters. The certainty with which I often hear (1) being declared or implied seems to miss this point.