Makes sense. I haven't used the design functions a lot, or at all.
Is it something I should really study and use?
IMHO, you should be familiar with all functions - at least to the point of knowing that such and such function exists. That said, the opportunities to use LayoutIDs are extremely rare.
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To avoid the issue of missing layouts which have been used in scripts, you might consider running a Database Design Report (DDR) on your files, so that you can check to see which, if any, scripts reference a layout before you delete it.
Then, in some cases you will know which script steps to update after a deletion, or, you can avoid deleting the layout, but copy the elements from you desired layout onto the old layout (after maybe deleting some all of the old layout objects). That will keep your script from breaking.