Good point, you do see some very wide downwinds sometimes, outside the ATZ even. I also do tend to climb further upwind myself, say 600', but it does depend which aeroplane I'm flying. You could also continue a climbing turn from crosswind to downwind instead.
All this of course is not really giving the OP what he was looking for, other than the fact that we fly steeper than 3 deg. approaches, which should make his maths work better.
Bemused1812
I think one thing you should do is get one instructor you're comfortable with and stick with them, that'll reduce the variables while you get yourself sorted out. It's a bit disappointing that two FIs at the same school haven't sorted themselves out with some common standards to teach though isn't it.