Probably 95% of the guys I worked with used milk jugs filled about 90% full for full jugs of ice and 50% full then fill the rest with water for drinking water during the day.
The log truck drivers did both because of the hot floor board but they had cold water all day long to drink.
The best jug I have found to date for freezing is the one gallon Lipton tea jugs with the green handle. My wife drinks two of them a week and we use the empties for drinking water when out and about and freezing 90% full for free ice for coolers camping. They last about three days in a cheap cooler more in an extreme depending of the heat.
Works great frozen in the RV frig to cool it down or keep it cool,then you have ice water to drink after.