Thanks for the explanation. I do think however that mentioning these shortcuts in the user guide would contribute to a more central overview. This is also why Alt+Tab, a windows shortcut, is mentioned in the user guide.
Just like Alt-Tab is necessary to navigate through different windows, hotkeys like Control+Arrows are essential for navigating large, non-empty excel files. Including these in the user-guide would give users one single overview of the essential shortcuts for excel.