Roger that... However, it only takes a minute or so to create a custom paragraph or character style, so it is a good practice to always include them in any template and not employ a series of empty paragraphs for spacing purposes. The custom styles do not need to set up with their parameters initially--just give the styles appropriate, useful names to serve as arrows in your quiver to use when needed.
If you intend to use subdocuments in a master document, you might want to take care not to use a generic term for a paragraph style, say Title, in all the docs because an automatic generation of a ToC would treat all such styles with that term the same--usually not what you want. To get around that, you might want to include custom styles named Book title, Chapter title, Front-matter title, etc.
Anyway, it is a good habit to start with some custom styles (as needed) right from the start when designing any template.
For practice, every so often I might take an OOo template, make some changes to it, then save it as a DOC file and import that DOC file into Adobe FrameMaker and see how that goes--usually (hopefully) pretty straightforward and flawless. FrameMaker is a much better medium for bookmaking in that crossrefs between external subdocuments are much easier to effect and thus are more reliable. Besides, FrameMaker is a hybrid word processor/DTP app that has better typesetting algorithms than a fancy word processor. (Adobe InDesign is even better yet). But that is my personal preference as to building books (master docs) for PDFs or print.
Also, MS Word makes beautiful tables with ease. So converting them afterward to another medium like OOo or FrameMaker can take advantage of that Word feature. You could create a series of custom tables in Word and collect them and convert them for later use in OOo or FrameMaker--provided that you do not mind using packages developed by private companies. Some people have hangups about using a proprietary software package or O/S.