The following article by Zach Johnson gives several methods for using long expire times on stylesheet caching but getting immediate results when you change the stylesheet.
http://articles.sitepoint.com/article/overcome-cache-conundrums
The methods he recommends would be rather cumbersome to do by hand. But changing the stylesheet filename by adding a variable string to the stylesheet url every time it is updated would be really easy to do in the CMS Made Simple Core.
This allows you to set an expire time of, say a week, and yet have instant results when you update the stylesheet.
A Trick to Allow Long Period Caching, but Update New Styles/Content Immediately
Re: A Trick to Allow Long Period Caching, but Update New Styles/Content Immediately
No one ever reads my tips lol 
here.. http://forum.cmsmadesimple.org/index.ph ... 682.0.html
This is the query way... and the udt to go with it... Thought I'd include that here...
Cheers
Jeremy

here.. http://forum.cmsmadesimple.org/index.ph ... 682.0.html
This is the query way... and the udt to go with it... Thought I'd include that here...
Cheers
Jeremy