When a person is praying for a personal benefit, is including all of humanity in the prayer a mistake because the energy of their prayer intention will be spread too thin to bring a good personal result? Is it advisable to do separate prayers for all on the planet?

This is an unfortunate reality that the reach of human is so constrained that one voice will not serve all. This is part of the natural balance of forces, to limit personal power in the context of the larger circle of beings who have a stake in all that happens. Under ideal circumstances, there would be power available to do many enhancements on a wide scale, because there could be checks and balances to limit negativity, but allow and even amplify positive intentions. This is a divine perspective and is the way the divine realm operates, in having an assortment of potential choices always available. But these will have inherent differences in their reach, based on the level of divinity they represent. The highest and loftiest of notions will have a greater reach, than a practical but personal outreach—will have less power if one simply wants to add others in, after the fact, to what is basically a selfish request—not meaning this in its usual judgmental interpretation, but only addressing a request made for personal reasons and benefit, and then adding some tagalong targets, as well, as a gesture of generosity, when the applicability may not even be the most appropriate. So there are many healers, and many modes of healing, and many perspectives, and places from which requests for healing may be launched, and all the differences in awareness. And therefore, the range of possibilities that can be brought into play will begin to influence what happens, and how far the healing might extend. So all the usual factors will pertain—level of belief in divine, level in belief in self, level of awareness of what is truly needed in providing the necessary context and array of options available to the divine realm, to follow the human lead with effective tools brought by them, at least through an intelligent request, as opposed to a request made in desperation with little belief behind it, or hope of rescue, and then not knowing the true reason for the threat, nor what can be done, and to what extent to make changes in the energies that are looming.