I don't think the fact that it looks like some are coming through in batches means they're putting others 'on hold.' They may just be getting processed at different speeds because their applications are different. There are lots of explanations for why it may look like it's being processed in batches.
For example it could look like that some notifications are sent out in batches (at a certain time of night or system updates only periodically), or if some approvals are done by some type of computer algorithm and signed off in batches, or if some are done in advance and then put on hold until some other step happens (eg LPP info collected and held until tests are complete).
None of that would imply others being put on hold. They're just taking longer at certain steps, but their processing could be happening in parallel - just slower for some parts. Lots of internal organizational / procedural or technical reasons could make it look like batches - particularly when all we see are some subset of 'updates' from people on the board.
Imagine a system where a cohort all starts on same week, each step takes from 1-7 days, system updates once a week, and at each step, one applicant from a cohort falls out / gets delayed for some period of time because that part needs more complex work (of a group of say, 50-100). And only half ever post, those who do - only when it's progressed. It looks like they're being processed in batches each week, but we're just seeing sampling/reporting gaps. Add some complexity (like each step actually takes 3-15 days, randomly within weekly cohorts) and conclusions about batches are just seeing things.
Humans look for patterns - and there are some patterns. But it's awfully easy to draw erroneous conclusions from the modest bits of info we see.