The guys at Irons and Ladders have put together a nice forcible entry video about the advantages and disadvantages of shaving bolt heads and plunge cutting. Identifying those bolt heads on the exterior of a door immediately let you know of the potential for alternative locking mechanisms. Identifying these features can make a dramatic difference in your time to force entry. Check out their video below. http://youtu.be/mmIQ5haWU3Q
Remember there are many huge disadvantages to breaking the glass out of a commercial storefront door. You will also run into doors like the one above; this door has additional security measures attached to the door. Gapping a commercial aluminum door can be challenging, especially if it has a deep set mortise lock. One option is to start at the bottom and gap as much as possible to use a rescue saw. You can cut the bolt but it will take a little while considering the hardened steel. Another option is go through-the-lock. Through-the-lock methods are often not understood or practiced due to a lack of training and understanding. An educated firefighter can generally perform a through-the-lock method faster than a conventional forcible entry method on these doors. If you are still one to say "Just Break the Glass", then consider the other implications. Not all doors that look like this have glass in them, some are lexan. Many doors have either interior or exterior bars that will hinder your entry even if you do break the glass. Finally, if you decide to take the glass you have just removed your shield of protection should the fire take a turn for the worst. A wide open entry with no ability to shut the door can cause ventilation problems among other things. If you were to break the glass on an interior entry, then you have dramatically effected your ability to create a barrier to hold back the fire's progress.