There's a ton of chances for there to be text you haven't seen before because of all the alterations. That causes the skipping to stop even if it is just one different line. So, it can be awkward to skip through this game.
The same text can appear in a different context. Sometimes lines are reused in a block of lines that does have differences, so even a line you saw in a different alteration branch counts as having "not been seen" in this new alteration branch.