My last employer had a really well thought out numbering scheme for the type of work we did. I have no idea what my current employer is doing with numbers, I'm not sure they do either. How you number jobs depends on whether it's a single operation or multiple operations/press rruns. Either way you should use an operation code at the end of the job
If you are doing work that is a single press run, and maybe went to a folder, cutter, or imaging afterwards I would do.........
12345-101
12345 being the job number and 101 being the opertation code. I would run all job numbers in chronological order having nothing to do with the customer,
Each customers jobs can be stored together in a file under their name. This makes it easier to locate because you will always know the customers name but you will never remember the number. You can easily tell which job ran in what order because it's chronological. for ex.....
Steves pizza
12345-101
12652-101
12784-101
Prep would only be concerned with the job number (12345)
Then you use the operation code a number of ways. -101 would denote a completely new job going to press.If the job had to be reprinted due to a mistake or shortage, you can use the same job number but change the op code to -102. (12345-102 for ex)
If you were printing another job for the same customer that is almost the same thing as a previous (maybe just some black type changes or something), you could use the same number but change the operation to 111 (12345-111). The only problem with this is that it screws up your shop"s overall chronological order, but I'm sure you have a date somewhere in the file. You can also just carry out the number order and then leave a note in the file that it is close to a previous job, but I like the other way better.
if it went to a cutter or folder afterwards they could use op code -201 to denote that it's a different operation on the same job. (12345-201) and they would use the -211 and -202 the same as press would