Here is one practical step you can take to support an autistic teen girl. Or any autistic teen, but this particular need is most common in conscientious fawners, who are frequently girls.
Ask her teacher how long she should be spending on homework, per night, on average. Then measure the actual time, and see how it compares.
If her actual time is a lot more, and that isn’t explained by co-occurring conditions like dyslexia or intellectual disabilities, then it’s very likely that she suffers from something I call “Everything Feeling Equally Important.”
The truth is, when it comes to homework, not everything is equally important.
It’s often okay to skim text for answers to questions, instead of reading every word. It’s also okay to study until you feel confident you can get 90% on a test (or 80% or 70%), not 100%. And “try your best” doesn’t mean the maximum possible effort – it means aiming for diligence and creativity.
She may not know any of this, unless the teacher tells her explicitly.
By default, when executive dysfunction doesn’t get in the way, I interpret directions literally and follow them thoroughly. This is because, like many autistics, I have trouble reading between the lines to figure out what isn’t necessary.
In high school, this caused me to spend way more time on homework than my classmates, leaving me with less time for sleep and personal interests.
My parents did express confusion at my workload, and suggested that I might be doing more than necessary. But I needed to hear that from the people who did the grading – my teachers.