I use whatever it takes with my boiloff rate to hit my desired gravity. Generally that falls around 75-80 min, but at times it is ~65 min.
are you using a refractometer to measure the gravity during the boil? unfortunately, I dont have one yet so i have to take a sample and cool it before taking the hydro reading, which can take up to 20 minutes to cool before getting a good read - i guess i should use an ice bath instead of the freezer to cool it quicker.
Does anyone have a recommendation for decently priced, yet reliable refractometer?