The other day I sat in a two hour meeting (hearing the work on my desk desperately calling for me), and considered the work/roles of several coworkers and me it occurred to me that jobs seem to come in two distinct groups:
(A) Jobs where, when you are not there, the work either gets done by someone else, or does not get done for good (Theoretical example: should a fire department collectively go on vacation for a month they won’t come back to a backlog of burning houses).
(B) Jobs where, when you are not there, the work piles up.
The difference being that legitimate absences from work (vacations, sickness, other assignments), with salary continuing to be paid, are not stressful (even relaxing depending on the cause) for type (A), but very stressful for the type (B) job. In my case, a three weeks’ vacation means a very stressful three weeks before (preparing all tasks that could conceivably come up) and a very stressful three weeks after (clearing the backlog).
The distinction between these types (A) and (B) is not along an axis of high/low importance, and neither along an axis of high/low qualifications needed.
Whether some job is in one of the two categories depends mainly on organization (one or multiple persons do a job, employee vs. self-employed, etc.) and only occasionally on the task.
For example, my job is in the (B) group because I am the only one doing it, the customer often requires work to be finished two or even one weeks after order, and it would take months to train a colleague to do the work half as fast as I do. If the volume of orders increased a hundredfold, i.e. I were one of a hundred, the same job would be in group (A).
So, is there a term of art for that distinction in types of jobs?