A few factors go into how frequent I water the Dogs, such as conditions like temperature, trail grade (hills), how much they are engaged (how hard they are working) and usually I can tell when they need a water break believe it or not sometimes they will actually start looking back at me:) So I’ll usually water them every 2 to 4 miles on average which is usually every 30 to 60 minutes… I water more in the beginning but as they get more hydrated, I usually go more distance/time in between water breaks as I mentioned sometimes up to 4 miles. I have always had good experience with letting them drink all they want on each water break. Hydration is so important but sometimes they are actually breathing too hard to drink all they want especially in warmer temperatures as they are panting to cool themselves also(that’s one reason warm temps can be so dangerous for them) heavy panting/breathing and drinking  can possibly cause bloat (their stomach to fill too much and put pressure on organs as well as possibly twist and or rotate and can be fatal) I will therefore on every water break offer them water at least 2 times. So this means we offer them water when we stop and when they are done we wait a few minutes after their first drink and offer them water again. I find more water breaks are better than less water breaks as they don’t get as thirsty keeping them well hydrated so they are possibly less likely to gulp it and less likely to drink more then they need possibly keeping them form bloating. Everything can be different from Dog to Dog and it’s always best to consult with your veterinarian as they will know your Dog and breed best and might have some other solutions, or ideas that may be more appropriate or work better for you! Again my suggestions work good for me but doesn’t mean they will work for others!