@Thrull: If you read that thread a bit more, you'll see reasons why your examples aren't going to work well. You already edited to point out why total lines isn't going to work. You also can't check the last lines because it's very possible to have two lines (or more) be the same. There are some examples of how to get accuracy up to around 99.9% or so (checking top, bottom, and at least one middle line... more increases accuracy) and for most things, that really is enough.
On the average channel, doing a bit of mid section checking should get you up far beyond 99.9%. But point taken, it won't be 100% and that can matter.
