I trace product every month to ensure the process is efficient and paperwork is accurate. Traces are "one up, one back," which covers all ingredients and materials entering the facility through the finished product being shipped out. The trace includes all information that I would need in the event of a recall. I created a checklist for product trace that lists all documentation necessary (i.e. daily finished product count shipped, daily production batch totals, combo labels, mixer batch log, mixer batch labels, bills of lading for ingredients and packaging, outbound shipping reports, make to order reports and bills of lading for finished product.
As far as lot codes are concerned...I need to be able to tell what day it was made, what production line it was produced on and the time it was made. Many companies use a combination of numbers to achieve this. For example, for today, 6/22/2016 you could have 174124, which means 174 (174th day of the year, found on most calendars), 1 (production facility #1), 2 (shift 2), 4 (line 4). Now you would know exactly where and when a product was produced by the coding. Going one step further, you could add a best by date with the time produced listed below.
In summary, you need to be able to find the necessary information needed for a trace/recall in a relatively quick time (~2 hours). Where did the materials come from and where did they ship to?