In Revit you can create and control your own keyboard shortcuts. If you use a (for e.g., the "Items in Room") command frequently, you can open this window with your own defined shortcut. Go to View > User interface > Keyboard Shortcuts. Search for the command that you want to create a shortcut for (for e.g., the "Items in room" command). Under "Press new keys" insert the shortcut you want to assign to the command and press "Assign":
