As seen in https://ask.libreoffice.org/en/question/203993 (see answers by jaragon and ZeroCarb), some users have difficulties with overlong menus. So such long menus should be revised to group some items into submenus.
Guideline https://wiki.documentfoundation.org/Design/Guidelines/MenuBar says: * Seek to have no more than 20 items within a single level of a menu and use submenus to assist in this limitation. Add separators between logical groups within a menu. Seek to organize the menu items into groups of 7 or fewer strongly related items. The main menu must not exceed the minimum requirement for display resolution of 1280x768px/WXGA (with common themes). This menu has grown in fact a bit too long. However, I'm afraid of touching the menu. Opinions?
The menu has likely been updated meanwhile. Insert is not the longest menu (anymore).