Why does “je devais” mean “I was supposed to” instead of “I used to need to”?

Question

The imperfect tense is supposed to mean an action in the past was (and possibly still is) habitual, repeated, or continuous? I don't understand how that would imply failure.

If someone said to me, "je devais aller chez toi," I wouldn't interpret that as a person not going to my place despite some requirement. I would understand that as they were repeatedly or habitually required to go to my place.

If I used to work as a business man and I was often required to show up for business meetings, wouldn't I say "je devais à les réunions d'affaires" to indicate that I was required habitually?

Answer 1

Actually it can mean both. If you said "je devais assister à beaucoup de réunions", only context would make it possible to tell which meaning was intended. Usually it tends to mean "supposed to" because, quite simply, when the meaning "used to need to" is intended, a different expressions is used:

J'étais obligé d'assister à beaucoup de réunions. "I used to need to sit through a lot of meetings."
J'étais obligé de venir chez toi. "I used to need to come to your home"