How to make sense of textures?

[Wobbaphony]

My guess is no.

Textures can be arranged as far as I know, in any arbitrary layout the developer or program chooses.
So long as the data is there to tell the program what to do with it, and the program has all the required code to read that data, each individual texture could theoretically be split into a bunch of 8x8 chunks, scrambled randomly, and then scattered randomly on a 10,000 x 10,000 texture file!

I have the same issue with MineCraft textures all the time, especially mobs!
And those are square/rectangle-based!

Another problem is that textures tend to look REALLY weird when not on their respective models sometimes.
So, while my insane example likely would never occur, textures might not be easily recognized.
Another thing is some textures may take advantage of lighting effects or masks. (Most note-able would be a metallic surface)

That said, I'm pretty sure textures are a trial-and-error kind of thing, unless you can find an actual guide for them, or if they're in some way, generally, rectangle-based (extremely unlikely).

Ah, alright, that's what I thought was going to be the case. Thank you for the info =)