There's no need to use layers unless you have to. Putting all of your artwork in one layer will not make any difference to output quality or processing time, so it's really a matter of personal preference.
Having said that, there are some advantages to using layers, eg you can switch off sections of your layout to make editing easier, but I generally only use them when absolutely necessary.
I would strongly recommend to work with layers as it improves production security and some tasks are impossible to do without layers. My recommendations are: from bottom up:
- Background: This will allow you to draw a background even on the master which will always be below anything else you work on the pages.
- Images: Images have often transparencies, so it is good to have them below text and vector graphics as they could force them to be rasterized.
- Graphics: For vector files like AI
- Text: For anything written
- Pagination: Pagination, headers and footers are done with placeholders on the master. To use them on top will keep them always above anything else like images or graphics or background.
Of course more possiblities are given.
It is important that layers are always in the same order in all files as it helps to copy and paste from one file to another and keep the order of items. (In the layer panel should be turned on Paste remember ayers.)
To change an item from one layer to the other (InDesign has no sublayers as Illustrator has) drag the item in the layer panel from layer to the other.
Using layers helps also to protect items when working on others. E.g. you might want to lock images and work on text and don't want to touch the images all the time.
InDesign doesn't really have sublayers—the items you see when you toggle open a layer are page items not layer items and are specific to the active spread.
Layers are document wide objects and can be essential for organizing complex documents. So you could have a text and image layer, which would allow you to hide or lock all of the text in the document and keep the images visible. If you tried to do that with a single layer you'd have to go through the document page by page and select each text frame. Also if you use master pages and have to release a master page item the stacking order can change, so with master pages you really want to setup layers for any overlapping items that might get released to a page.
Thanks everyone and sorry for the slow reply. I seem to be able to work with the page items ok since I can re-order, turn on an off etc like full layers. I haven't seen any real difference but I understand that they take on characteristics of the parent layer? Thanks for the further info though - really helpful. I'll see how I get on.
Layers have no characteristics itself like in Photoshop or as it would be possible in Illustrator. InDesign is an Object Orientated program. But layers have a kind of ordering.
Every item on the same layer on a page is above any item of the master from the same layer.
But any item of a layer above from master and from page is above any item from any layer below.
This makes layers important. Without layers it would be difficult to keep the page number or any running header or footer from placeholder frames above without overriding them. Overriding should be avoided.
I think working without layers makes many tasks impossible to perform. So it is always a good idea to use layers.