Learn English – differentiating between “as soon as” and “when”

I think what your English teacher told you is right, as far as it goes; but there is a middle ground it does not address, where either may be used. I imagine that very often this is what you are hearing.

The even clause may be neither hypothetical nor concessive but 'occasional'—that is, it may refer to a condition which is sometimes true and sometimes not. In such a case you might use even if or even though, because both are contextually equivalent to even when:

You should eat breakfast every morning, even if/though/when you're hung over.
Even if/though/when he's sometimes over my head, I enjoy Prof. Sartorius' lectures.

In formal contexts you would probably adjust these sentences a little to fit the conjunction more precisely:

... even though you may be hung over
Even when he's over my head ...

But those are niceties which are not required in ordinary conversation.

The first assumes that a time will definitely come when the speaker’s need for the object comes to an end. The second makes no such assumption.