Regarding Ice Bridging: The NASA Glenn Research Center did an exhaustive icing study recently and concluded that bridging was a myth. (I'm not trying to argue any point here, but just show the new thinking on this subject contradicts what many of us were taught).
The latest AOP writing reflects the Glenn Research Center view.
See "Boots" on page 6:
http://www.aopa.org/asf/publications/sa11.pdf
See "If you got 'em, pop 'em":
http://www.aopa.org/pilot/features/inflight9910.html
And here's a cool NASA online course about icing:
http://aircrafticing.grc.nasa.gov/courses.html#
Under the section "Aircraft Designs for Icing-Deicing Systems" it makes some interesting statements, such as:
1) Waiting to inflate the boots can be dangerous
2) Ice bridging simply does not occur with modern boots
3) If you begin to accrete ice, activate the deicing system immediately and cycle continuously. Do not wait for a certain amount of ice to accrete, unless the AFM directs otherwise.