Suppose that Sam is dying of cancer and Sally prays for him. God now has two reasons to cure Sam's cancer: (1) cancer is bad; and (2) Sally has asked God to cure the cancer. Simplify by supposing these are the only two reasons God has for curing Sam. And presumably there are reasons against curing Sam, such as that miracles damage the order of the universe or that Sam can learn much from suffering.
So, God has to make the decision whether or not to cure Sam. Question: If God is going to cure Sam, does God always have to make an additional choice whether (a) to cure him only because of (1), or (b) to cure him because of (2), or (c) to cure him because of both (1) and (2)?
I think that supposing an additional such divine choice wherever there are multiple sufficient reasons for acting is not particularly plausible. God then would need further reasons in favor of each of the three alternatives (a), (b) and (c). There may be some logically possible cases where God a reason to cure Sam only because cancer is bad, and not because Sally asked him. Maybe this is a world where God promised to ignore Sally's prayers on that day, to teach Sally a lesson. (I doubt God makes such promises in our world.) But typically, there will be no reasons to prefer (a) or (b) to (c). So, typically, God will only have reason to go for (c), and so he won't have to make the additional choice between (a), (b) and (c), since where all the reasons are seen to favor one option, no choice needs to be made.
This leads to the idea that at least typically, when God does anything, he does this for all the reasons that favor doing it, rather than for some selection of reasons. This is an aspect of what I call "divine omnirationality."