Definately! Otherwise you have to redo all the LSP and CUI customizations after an upgrade. Each time you install a new version that path changes (at least the <version> subfolder).
The trick is to create a folder like C:\MyAcadCustom\, then add it to the ACad support paths. And to make sure your own acad.lsp & acaddoc.lsp is loaded instead of any other, move it to the top of the support path list.