On average how many repairs in a one bottle of windscreen repair resin?
Assuming you are using a Delta Kits Bridge and injector, Delta Kits recommends 14 drops when using our glass pipette dropper and 7 drops if using our older style plastic pipette dropper. (The dropper volume is different between the glass and plastic dropper) It is essential that you dispense the resin as deep as possible into the injector barrel when using in a top loaded injector as is the Delta Kits Injector.
Now back to your original question, by using the guide above you can expect a minimum of 50 repairs from a 15ml bottle of resin. Cracks are a whole other topic, no good answer for that, too many variables. If referring to a 7ml of Premium Pit Resin, well over 100 repairs.
Below is a video showing the correct application of resin into a Delta Kits Injector.
Going through a lot of resin? Delta Kits offers bulk windscreen repair resin.