Leave it on a slow trickle for a good 45 minutes to an hour. After that your tree shouldn't need any more water than what Mother Nature provides, unless there is a drought. By watering deep and infrequently you are making the roots of the plant grow deep. This is better for the plant, as it will help it become more drought tolerant and better anchor it into to the ground. By watering more frequently and for not as long the roots of the plant will be more shallow.
Sprinklers are better than nothing most of the time.
However, sprinklers are not the ideal way to water plants, other than turf grass. The water gets on the leaves and needles of the plants when you use sprinklers. Plants can only absorb water through their roots. The water on the plant's leaves and needles evaporates, taking extra moisture from the plant with it. To the extent possible, you should try to water early in the morning.