Actually all the custom content my team creates I usually have made at 25fps because it runs better. Other times I'll just re-render stock content to 25fps.

The only time I worry about running 30fp (29.97) is when I am interfacing directly with TV or if the cameras of a shoot will be capturing a great deal of the video screen sets. Even in the case of the video screen sets, I still don't notice a great deal of flickering caused by frame disparity or mismatched scan rates. Actually in this case I am usually much more worried about color correcting and green shifting the projectors anyway so that the cameras actually see white light.