I admire your dedication, but your method is flawed.
If you consider each VOB file separately, you'll omit some frames.
Looks like you're missing three frames in this case.

negative1 said:
00:19:19.659 27524 27804 p r2d2 joins luke and c3po
00:19:21.285 27805 27843 b fade to black
00:19:22.370 27844 27869 p c3po fading in

negative1 said:
00:00:03.795 0 91 p c3po fading in (start vob2 - part 2/2) total 29758
00:00:15.056 92 361 p luke in repair room

You've got 281 + 39 + 26 + 92 = 438 frames

On the other hand, if you concatenate the VOB files first
or if you use DGIndex, then you'll get:

27524 --> 27836 r2d2 joins luke and c3po
27837 --> 27964 c3po fading in
27965 --> luke in repair room

27965 - 27524 = 441 so you've missed 3 frames