Is daily prayer really necessary?
We don't recommend "daily" prayer; we recommend praying at every moment.
The more we understand how tiny and vulnerable we are in the face of the material energy, and how much we're at the mercy of forces beyond our control—even for the most routine and seemingly automatic activities like breathing, digesting our food, and keeping our blood circulating—the more aware we become that we need significant help just to live in this material world.
Those who are in pure Krishna consciousness are fully conscious of this, and because of their developed devotional consciousness are also always wanting to serve the Lord at every moment. All religious practices are meant to bring us to that point.
Thus, the more we pray, the better. The most selfless prayer—and the one most pleasing for Krishna to hear—is: "Dear Lord, please engage me in Your service." This, of course, is the most common translation of the Hare Krishna mantra.