In my opinion, (as I have argued how candor conduces to greater harmony), being forthright is more important than momentary sensitivity. The end to sensitive behavior is establishing long-term harmony. This is not possible if the relationship contains defects which are ignored (because we keep on editing out the part of our message that cites such defects, in order to avoid hurting feelings).
In some cases it is acceptable to have a defective relationship (E.G, acquaintances, work related, and in certain cases of friendships), where you would be able to allow the defects to remain. In those cases you can forego the directness and just be 'sensitive'. As given how insignificant that association tends to be, it probably isn't worth the trouble fixing the relationship. As to be clearly noted, you can get all you'd want from the relationship whilst having it defective. A perfect example of this would be an acquaintance or a co-worker, with whom you do not require a high-level of harmony.
But again, bottom line: if you want your relationships to work on a profound level (which many NFs do), you must put candor ahead of momentary sensitivity. Failure to do so, in my opinion is the main reason why many Fs are dissatisfied with their intimate relationships.