Not exactly. Its part of knowing the in's and out's of the program.
Toolbars/CUI/workspace pretty much go together. Custom toolbars and other UI content should be in your own custom CUIx files. That way, you can create a copy of the file and use that with the new AutoCAD version. Partial loading helps keep things organized. I don't recommend sharing those between versions. Workspaces should be built from scratch. Why? Well, they reference all the used UI elements, and that includes the OOTB AutoCAD ones. Those can change between versions, more so when you skip several. Its best to set up a new, clean workspace so you don't carry forward legacy content and are aware of any additions.
Custom tool palettes are much the same. You'll want an isolated copy for each version - once opened by a newer version of AutoCAD they'll be read-only for earlier versions.
System variables can be a bit tricky. If you don't have an automation system to control these for you, you should be keeping track of what you change from the default settings. That way you can replicate those changes in a new version. BUT you also need to consider changes in the new version. Some are deprecated (BLIPMODE is a good example) and should not be carried forward. Some are new and require investigation and understanding (and logging, once changed).
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If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.