Zuzu ...
That's the method of watering I use in this garden. I found a sprinkler head that puts out a round spray and set it under a rose and water under the canopy of the rose. I use a kitchen timer and adjust the amount of time I water each rose to the size of the rose, to make sure they get a deep watering once a week.
Even during the high temps of summer, it has worked well. However, when we have triple digit temps for a week or more, I often do what I call a "feeder root" watering mid-week. Since the feeder roots are closer to the surface, I don't have to water as deeply and I will generally water the whole bed so that the dryer soil doesn't wick away the moisture from the rose.
It doesn't work for every rose, but I'd say it works quite well for most of them. Some roses seem to need a deep watering when temps are that high at least twice a week.
Smiles,
Lyn
