grammar - "While" followed by simple past/past continuous

I'm currently reading "Molly Fyde and the Parsona Rescue" by Hugh Howey.

Here's a short passage with my problem zone and the subsequent question:

...Well, I'm going to go do more Officser sstuff," Walter said
haughtily. "The sstorage lockerss in the bilge are almosst done," he
added with pride. While she waited for Walter to pad away, Molly

noticed how close her face was to Cole's. The nav screens were hard
to see clearly from an angle. ...

1. Why is the simple past used and not the past continuous as in

While she was waiting for Walter to pad away, Molly noticed how close...

1. I thought "while" contains the element of duration and hence requires a progressive form?

2.1 BTW, is the above question even grammatically correct? Or should it have been

• "I thought while contained the element of duration and hence required a progressive form?"

I read something about verb tense consistency within a sentence and to not switch from one tense to another unless the timing of an action demanded that you did. Is this the case here?