Long consecutive numbers come from the dark times of our forefathers.
Nowadays we can search and find with computers much faster than any human could ever do. That's why our numbers are designed so that they can be found quickly via keyline search.
The keyline numbers are always 6 digits, consisting of letters (A-Z) and numbers (0-9).
Therefore it is sufficient to search for the order ER-5F-JW only for "ER" and the probability to find the search at first go is very high.
If you had a consecutive number range, many more characters would have to be entered. In addition, a shorter order number is also more customer-friendly and easier to remember.