Quote from VK2FAK
But really....what benefit is there to copy a call sign at say 70 wpm but you can only send at 40wpm(max) and you can only QSO at around 35 comfortably...just as an example..
Now if it was a complete sentence of say 10 words...now your talking.
Contesting and DX'ing CW speeds rarely exceed 35-40 wpm. Conversational CW speeds can be much faster than that. When listening to a conversation, one has the benefit of context to help in decoding the words. Copying call signs on RufzXP requires accurate decoding of each character. It is good training for improving one's code speed for whatever interests you have.
Learn CW Online is another resource for code practice that offers the option of complete sentences and paragraphs at any speed you want. It also features call sign and word practice modes. See: http://lcwo.net/