http://blogs.wankuma.com/rti/archive/2008/09/26/157515.aspx

It’s such a pleasure to come across recently learned things in the real world.

Bshock-san, I love using them, as the listening party always seems to get a kick out them.

マイクさん, yes. Mayumi did the research for these. They are really something! And they get better.

Stephen-san, thx!

Highbridge-san,

Christmas Burgerさん、久々！ Who said that word?

Eric-san, ありがとう！

Alainさん、 as always, thanks for that great info!

stop by my blog if you have time!
http://lunchmaniac.blogspot.com/

We read yojijukugo in newspapers or novels, rather than hearing them in conversation. We use some very popular yojijukugo in our daily conversation, like 一石二鳥 as you said. I think when you use 四字熟語 too often, it might sounds like talking with a knowing look. But, when we want to say something in short, or when we want to make your writing look more sophisticated, we sometimes use 四字熟語.

However, I am not at all clear about the appropriate instances to use 四字熟語. In English, such expressions might be considered cliches to avoid, and frequent use of them might mark you as a boring writer or speaker. But I have read that the Japanese consider stock expressions to be comfortingly familiar and perhaps wise, sort of like “cultural code words.”