This was the advice I was given when someone edited mine:
Honestly, just having a
"I 100% plan to matriculate if I am accepted" will already be sufficient to get the message of "I have a strong intention of going there" across. Some additional fluff can be added, but the most important part of your letter that will carry the most weight and influence the decision of the committee is the sentence underlined above.
You can even title the subject title as "Letter of Intent and App Updates - Insert Name" and that's all they have to read honestly to leave a "this student will accept our offer" memo on your app.
Then, you can also have another section for updates. "Also, I would like to provide the committee on significant updates. First, this. We did ___ and this ____. Secondly, I did ____ because _____. Etc."
And just end with a simple "Thank you again for considering my application. Again, I would be deeply honored if I am selected to attend HCOM. I look forward to hearing from you!"
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I think mainly you're just showing that you would 100% go to their school if you were provided with an acceptance. Which is nice for them, because then they don't have to try and keep refilling the same spot as people decide they don't want their seat etc etc.
I actually think this is the document I looked at two years ago haha:
Learn when and how to send these two types of update letters to get off the waitlist and into your dream school
www.shemmassianconsulting.com