Loop Over Items gotchas I tested: one array item vs many, Done/Loop outputs, batch size

Tips & Tricks
1

I ran a few Loop Over Items (v3) tests on simulated data and wrote down what surprised me, in case it saves someone time:

  1. An item holding an array of 5 records is still ONE item. Use Split Out first, or the loop runs once. In my test, five rows came back all with the same ID (R001) even though the row count looked fine, so check IDs and not just counts.
    1. In the exported v3 node, Done is output 0 and Loop is output 1. Easy to wire backwards.
      1. Batch Size 2 on 5 records ran as batches of 2, 2 and 1. It does not add any delay between batches, so use a Wait node if you are rate limited.
    3. I put the full walkthrough and the other fixes in a free guide with a lab you can run, no signup. Disclosure: I run that site, so it is my own: n8n Loop Over Items: Easy Setup + 7 Common Fixes
  3. Happy to correct anything that differs on your n8n version.