Tire Chains... when to take them off?

I live in Texas and put tire chains on my car so I could get around.  The roads in my neighborhood are still like skating rinks, with only a few patches of exposed pavement.  Most parking lots are icy, slushy, etc.  However, the major and most secondary roads have least one cleared lane with only occasional icy patches (bridges, in the shadows).  

I know I should minimize driving on pavement with the chains on, it can damage both the chains and the tires.  But, I still really need them in the places where there is still ice and deep slush.  

Any recommendations?  What do people generally do when the conditions are so mixed.  My inclination is 'better safe than sorry,' which would suggest it is better to leave them on until I am sure I don't need them any more.  It is cheaper to replace the chains or my tires than potentially pay for repairs to my car and towing fees.