You might also want to look at the behaviors associated with job group imposition.
If there are not enough documents in a job group to fill the press sheet the jobs the jobs will not be imposed. Instead they will pass through. You could use this to a similar effect without having jobs in a loop.
Also, the Collect node can aggregate jobs until a specific number of jobs are collected. This can then be passed to imposition for automated ganging.
Collect can also release jobs after a certain amount of time so you can go to "plan b" for imposition.
I think that's a more practical implementation vs looping constantly as you may decide that you need to fall back to plan B if not enough jobs are collected.
Additionally, if you upgrade to v22.214.171.124 (released on monday of this week) there's an option to route by the number of documents in a Job Group
When Collect releases jobs can aggregate them into a job group.
Beyond that jobs are submitted as a job group if
If you would not mind, I would like to understand what you are trying to implement which would require routing by the number of jobs.