It may be important to realize that highlighting a layer and selecting a layer are two very different things in Illustrator.
Highlighting a Layer allows you to perform layer operations, such as move the layer in the stacking order, delete the layer, duplicate the layer, etc. Highlighting a layer does not give you the ability to edit the objects in that layer, only the ability to alter the layer as it pertains to the Layers Panel.
Selecting a Layer means you are actually selecting the objects contained in the layer, the artwork, as well as the actual layer itself - giving you the ability to add Appearance Panel adjustments at the layer level.
You can Highlight Layers, as mentioned, by holding down the Shift key and highlighting the first and last items you want to highlight.
Note that in the above animation only the object on Layer 8 is selected, but not Layer 8 itself. The Shift key is being held down.
However, to Select multiple layers, the "spanning" ability does not exist. You have to hold down the Shift key and click each and every target for the layer.
Note that in the above animation the Shift key is being held down.
And, if you are seeking to select the objects on the layer but not the actual Layer itself, you click to the right of the circle target....
Note that in the above animation the Shift key is being held down.
There's no shortcut for multiple selection of layers (or objects on the layers) other than actually using the the artboard(s) to select what you need selected. But if only using the layer panel... you have to Shift-click-click-click-click. There's no way around that I'm aware of.
And, of course you can combine selecting and highlighting (not sure why you'd need this though) and using the Command/Ctrl will allow you to highlight non-continuous layers.
Note that in the above animation the Shift and Command/Ctrl keys are being depressed.
If you have the need to repeatedly select the same objects, on various layers, you may find the menu item Select > Save Selection
very helpful. This allows you to select something once, save it, then when you need to reselect those same objects, the saved selection will be listed in the Select
menu.
This isn't a widely used feature from what I see, but it's been around for some time. In addition, the Save Selection
will honor layers without the need to combine everything on a single layer (like a Group). So... really it may be troublesome to create the first selection, but you should only have to do it once.
Shift.
" – vectorboom.com