I use the N-Dash a lot - not too often I use the M-Dash - unless it’s to show a pause - and them I usually use ....
They are also used to to indicate breaks or cutoffs in speech when writing bookw, usually fiction.
Fred looked at Galena like she had three eyes. “Ypu seriously think i give a rats rearend what—” (actually they use an M dash or em dash, not the two dash lines)
Galena shot Frank an atomic stink eye from one of her three eyes that glued his flappy yappy lips shut mid sentence. He knew that if he continued, he would be ‘what’s for dinner’ that day.