Hi,
Production at the Royal Mint increased sharply in the early 1870's for nearly every denomination produced. In my opinion an employee could be assigned a range of die numbers or die numbers taken from a particular range. Lets take the 1879 half sovereign as an example, we know that production of this rare half sovereign was completed on one day the 6th December 1879 amounting to mintage of approximately 35050 (my figures) with 10 different die numbers being recorded. Gold being a soft metal this would give an average production of 3505 per die which appears very low especially if compared to the previous year, where the mintage was 2,317,558 and 89 recorded die numbers so far, giving an average of 26,040 per die. if the dies were handed out to more than one operative this would make more sense. Die numbers recorded for 1879 are:
57 & 58 (57 also recorded in 1878 but not 58)
88 & 89 (not recorded in either 1878 or 1880)
95 (not recorded in either 1878 or 1880)
112, 116, 119 (119 also recorded in 1880)
161 & 180 (only recorded on the 1879 coin)
How many different operators are involved in this production run could be 1 could be 10 but more likely 2 or 3
I think by 1873 the futility of using die numbers had become apparent to the Royal Mint and this is why the the new Sovereign and the re-introduced half crown did not have die numbers.