Clay is right - too much of the Fe #2 will cause white specs. The basic issue is that Fe #2 is a contrasting agent - you substitute Fe #2 for Fe #1 in order to increase contrast, but as the concentration of Fe #1 decreases, the sensitizing solution becomes weaker.

A better approach is the method described in the article in the latest View Camera in which the NA2 solution is used instead of Fe #2. It only takes a minute amount of the NA2 solution to achieve a far wider range of contrasts than you can get with Fe #1. And an added benefit is that the NA2 approach uses only Pd salts, and that saves money.