In a program I once wrote, all menu items could be added to the toolbar. The toolbar (optionally) didn't have text (other than the tool tip.)

Having the icon in the menu acted as a visual link so that the user saw it in the menu, then in the toolbar.

The icon was reinforced as part of the header on the window the user went to. In other words if they clicked a menu (or button) with that icon, then they got a window with that icon.

It helped that we used color icons, so the colors also indicated something of the nature of the task at hand.