All the HR guy did training for me said do talk for salary negot

All the HR guy who did training for me said do talk for salary negotiation, I guess this is because they all speak good English.
I always do negotiation in face to face talk.
However many of the friends at here do successfully adding multi thousands dollars to their base salary just by a simple email (like 草梅派 一妹儿, 小鱼儿家掌柜的一妹儿, 详见 101), I guess all of them are not as 脸皮厚 as me, therefore, they (and you) like to use email.
Which way is better?
The DATA shown that both ways worked well, as I said many times previously: DATA is EVERYTHING.
We already got the data, we trust it. Not need argue.

Thanks!