There are TV shows that have telecined film segments and also interlaced VFX sections. While this wasn't broadcast as VFR the best way (as in highest quality result) to convert to a fully progressive frame sequence for display on modern displays would end up recombining the two fields for telecined segments (keeping the framerate) while doubling the framerate during deinterlacing for the VFX segments.
But VFR is also irrelevant to the problem at hand since it doesn't make it harder to find the next keyframe before the current frame - you need an index for that anyway.
There are TV shows that have telecined film segments and also interlaced VFX sections. While this wasn't broadcast as VFR the best way (as in highest quality result) to convert to a fully progressive frame sequence for display on modern displays would end up recombining the two fields for telecined segments (keeping the framerate) while doubling the framerate during deinterlacing for the VFX segments.
But VFR is also irrelevant to the problem at hand since it doesn't make it harder to find the next keyframe before the current frame - you need an index for that anyway.