If you are talking about B&W then fog is really not an issue. You can just print through the fog.
Loss of contrast is a bigger issue but again with B&W it is easy to adjust for as long as you have several rolls of film from the same batch. Once you know how to develop one roll you can use the same method for the other rolls in the batch.
The real issue is fade of color dyes and the fact they fade at different rates. Low temperature will slow down the fade of these dyes.