Needless Inconsistency

I'm using a smart phone with an OS that shall remain nameless (to protect the guilty), but I've found three different screens where three different operations are required to back out of a sub-menu or screen if it's been entered by mistake. There's a button with an arrow pointing left, which sometimes does it, sometimes it's necessary to touch a "cancel" button at the bottom of the touch-screen, and sometimes a menu must be opened to find the "cancel" option.

If I was playing a game it might be fun to search for these things, but here it is just tedious.

A good UI picks a small, powerful and intuitive set of interaction "patterns", preferably aligned with existing experience, and uses them everywhere. Otherwise it's like having to learn 1,000 verbs of a language when only 10 are necessary.