<p>I've not seen ones from HS teachers for UG applicants, but I've seen many many many hundreds written by professors for grad school applicants. And just as many written by professors for professors when considered for promotion and tenure. </p>
<p>Universally such letters are positive if not very so (or most letter writers would decline to write one I believe). The numbers and checked boxes are ignored unless something jumps out in the negative or it aligns with another letter writer (and universally those checked boxes or numbers are all in the high category too). So I think finding out you have a glowing letter or lots of positive checks may not tell you very much. </p>
<p>Then again, do you think HS teachers might be different? That is, do you think they'd agree to write letters to your dream school for you (which takes a lot of extra time in their busy schedule), but often choose to write negative or neutral letters that thwart your chances? With that logic, then you should be thrilled if you are the more unusual student who actually gets a glowing letter! Maybe an adcom on here can tell you what they get to see on a regular basis. </p>
<p>Given the great bias toward the positive in most letters that the readers like me see at least, most of the time we are looking for anything negative at all, or reading between the totally-positive lines. Also short, generic or ho-hum positive letters aren't useful as it's tough to make a strong applicant really stand out among all the universal positive letters with generic, global statements (and not enough specifics to justify the statements). (as an aside, as a frequent letter writer myself I have on occasion wanted to say "but this person REALLY REALLY DOES WALK ON WATER!" knowing it's hard to be heard in the din of so many cheering for their applicants). Unfortunately generic/ho-hum letters might as easily be a reflection of the letter writer - ie lazy, busy, unaware of what's needed, or a poor writer- rather than a reflection of how they feel about the applicant. I think the lesson is to find not only letter writers who KNOW you and can say lots of positive but <em>specific</em> things about you, but also who are the kind of people who will put a lot of work into it (e.g.they are say diligent, detail oriented, organized, always go the extra mile for students). </p>
<p>Finally, I think its unfair (if not arrogant) for a teacher to suggest their letter is so great you will get in. Do they know what your competitions' letters look like? It's probably a small part of the whole thing and again, with everyone writing such great things about so many, how much difference can it make if its positive? It's a nice compliment to themselves I suppose, but they shouldn't get your hopes up too high either. </p>
<p>On waiving I think it's a good idea because it simply shows the teacher could be more honest and forthright, knowing you would not see it. I'd say 90% of the letters I see are waived, but it doesn't change the positiveness.</p>