Reciprocity failure comes up all the time in daylight when shooting with pinholes. The problem is that doubling the exposure time no longer results in doubling the effective exposure, so additional time is needed. Compounding that over a number of attempted doublings can lead to large increases. The program Pinhole Designer can output a small table in Excel format that can include compensation for reciprocity with a number of popular films. The results are quite sobering. The table is indexed by the shutter speed measured for f/22. That value is multiplied by a factor related to the pinhole aperture relative to f/22, a factor that can be well over 100, and then compensated for reciprocity. With a typical pinhole, a reading of 1/4 second can call for a four minute exposure! And a few stops beyond that, it starts calling for hours.

It can turn out that some films like Acros 100 with lesser reciprocity failure can effectively be faster than 400TX at long exposures.