> I'd be curious to know if anyone here actually uses the ctrl or alt keys that are located on the right.

You must be located in the US, because the US is probably the only keyboard layout with a right Alt key. All the others have an AltGr key in that position.

I use the right Ctrl key in combination with the arrow, Backspace and Delete keys. Also with Return to enter the same content in multiple cells in Excel.

"All the others" is a rather drastic overstatement. Some European layouts do that. Many non-Latin layouts do not, however. E.g. I can't think of any common Cyrillic keyboard layouts with AltGr.