I have seen many InDesign Data Merge questions about how to create sheets of mailing labels, especially the problem of getting only one label per page, when you need 30 or more.
Adobe's instructions are poor and incomplete in that InDesign doesn't step out the records from a data source - it steps out the FRAMESthat contain the data field placeholders.
That is why you only need to place a text or image frame once on a single page - during the datamerge, InDesign will create the additional FRAMES for each record, and it will create the pages required to hold them.
You do have to set the desired spacing on the
If you create the frame on a Master page, ID allows you to update the data source (when it changes) in the Data Merge tool panel.
These are very nice and robust features, but the documentation for them is confusing to many people.
You will find more great in-depth help for Data Merge, with screen captures and attachments, here in the forum.