Some (not all) factors that would affect weight loss during drying are:
1. Humidity in your fridge (humidity fluctuates in most fridges depending on the contents, time of the year, type of fridge, etc. etc.)
2. Placement of the meat in the fridge and amount of air circulation it is getting.
3. The ph of the meat being dried and the size of the piece.
There are actually too many factors to list. The system is designed to work with many fridges, but it is impossible to predict exact drying times.