When creating visual mode maps, you prefix ex commands with
<C-u> to clear out the range if it's unused:
:xnoremap % :<C-u>execute 'normal! gv'<Bar>call Percent_nextline()<cr>
(example from How to make a movement function work with delete, yank, etc)
But is there any point in doing so for normal maps? I can't imagine any scenario where a normal noremap ends up with text in the cmdline.
In summary, do I ever need this:
:nnoremap % :<C-u>call Percent_nextline()<cr>
:nnoremap % :call Percent_nextline()<cr>