Sutra lectures are very formal events. Before each lecture, we’d perform a Dharma request procedure in order to:
That’s why a purist would frown at listening to Sutra lecture recordings while engaging in other activities.
We feel that one should be more flexible and accord with the conditions (environment). Therefore, it’s better to listen to those recordings while driving, working, or walking, etc., if it replaces other not useful activities such as daydreaming.
However, please make sure to pay attention to the task at hand. For example, if you enter samadhi while driving and listening to the recordings, it may cause more harm than good.
Furthermore, we assume that when you mentioned “while working”, you meant while at work. For example, a night watchman at work, a computer operator at her console, etc., all these instances require minimal mental processing and thus the mind can register the lecture materials. Even so, keep in mind that the materials can only be efficiently registered in proportion to the concentration level.