Well I learned a lot my first full winter in SD after always being in Tx or else where in the deep south for winter time. I learned that a chip in my 1969 ford p.u. windshield would not only crack when hit with hot air when I switched to defrost from the heater setting after getting the cab really really warm...I also learned that I could hear the crack and watch it run across the bottom of the windshield from one side to the other!
During traffic stops in both Tx where there is/was a yearly inspection or no tags....and in SD where at that time there was no required inspections, the cracked window In both stops was remarked on by LEO's, also the location {bottom} was mentioned and that it was not eye level or in my line of sight, so I guess it wasn't a issue at that time.
I've had other vehicles up there with window chips and spent plenty of winters too. One trick a old timer told me was to clean chipped & cracked spots with alcohol and let dry. Then use clear nail polish [ I use Sally Hanson with nylon fibers from Wally World] on the chips and cracks, I'm not sure if this works or not. The only time I've had a a cracked windshield since the 1969 truck was when a lock out service cracked mine at a truck stop in South LA.
and they replaced it very quickly! I don't know if I was just lucky or this really did help. I also began turning the defroster on when first cranking the truck and set in on low fan and low heat and as soon as possible turn the defroster off and run the heater on floorboard or panel settings.
The second time I moved to the frozen north [ I like it up there] I also used cheap small tarps when snow was forecast and pulled them over the windshield, some of it up on the roof and closed the sides up in the front doors. Next time I used the truck I'd just pull off the tarp and the snow went off with it. I hope this info helps out. Texas Jbird