I notice people in mainland China use abbreviation for almost all titles.
習總裁 --> 习总
郎(平)教練 --> 郎教
任隊長 --> 任隊
This kind of abbreviation even appears in Hong Kong's TV dramas.
王法官 --> 王官
張大狀(大律師) --> 張狀
I personally think shortening a two-character word to a single-character one is too casual and may cause confusion (I am sure we will only find 习总裁 and not 习总 in official documents).
习总 and 杂种 sound the same in Cantonese
任隊 in Cantonese sounds like "allow to stab at will"
王官 and 皇冠 sound the same in Cantonese
任总督--> 任督 make people think of 任督二脉 and sounds like "allow to poke at will" in Cantonese
Question: Is not abbreviating titles in casual conversation considered normal in Mainland? (in other words, I wouldn't give it away that I was not a mainland Chinese by saying 郎(平)教練 instead of 郎教)