Wonder Lister
User guide

Explain the difference between one-at-a-time-submission versus Submission-as-a-job

In Wonder Lister, you can submit multiple items (templates or listings) at the same time. Based on the number of items submitted, Wonder Lister can submit to eBay in one of the following two ways.
Submit one item at a time
Wonder Lister send one item at a time to eBay, gets the result of that submission and then sends the next one and so on. So, if you have submitted say 1000 items to eBay, Wonder Lister will make 1000 trips to eBay - one trip per item.
Submit as a batch
Wonder Lister internally prepares an in-memory file that consists a bunch of requests and that in-memory file is then sent to eBay as a single request. It is called a Job. eBay servers are responsible to process those bunch of requests in the Job and returns one composite response per submitted Job. So, Wonder Lister may have to do just a few trips to eBay. Typically this process is much faster than "Submit one item at a time" method but of course depends on how many items were submitted to start with. The disadvantage of this approach is that it needs more memory as the requests are grouped together in a memory file until they are all ready for submission. If you feel, your batch submissions are slower than one at a time method, you should increase the Batch Cutoff Limit.
To monitor the status of jobs submitted to eBay, use the menu option
Tools > Options > Jobs submitted to eBay
Clicking the option "Jobs submitted to eBay" displays a new window.
By default, the cutoff for deciding whether to submit one item at a time or as a batch is 5. So, if 5 or more items are submitted, Wonder Lister will submit them as a batch. However, you can change this cutoff limit. See Batch submission cutoff limit