Anihunter said:
Now here's the question I have to ask- if the scene was animated both on ones and twos, would a combination of both delays work?
It should, but only if you remove the repeated frames and adjust the timing accordingly.

This is my workflow whenever I bother doing this:

1. Save the extracted frames in a folder and delete all the redundant ones.
2. Load the remaining frames into PS and apply a 0.04s delay to all frames so I don't have to bother with ones.
3. Use the filenames of the remaining frames as a guide when changing the delay. I have commands in PS for up to a 0.20s or fives delay.

You'd usually have to go through each frame since the erratic timing in most anime doesn't help. Not exactly something I'd recommend. This also doesn't work if the scene has camera movement because that is almost always on ones. Don't bother if the cut has a ton of things (e. g. two or more characters/objects plus FX) going on since there tends to be something new in each frame.

The only reason to do this is to reduce the filesize anyway. Most of the time it's more convenient to just dump all of the frames, apply a 0.04s delay to everything, then see what you can get with dithering and color settings.