Ignore the standard man... never heard of such a thing ... it's tosh.
As a good rule of thumb, height of archer plus maybe 2" but for warbows you can go up to about 80"
As a guide I'd say 70" will be a good length for a medium heavy weight at 28"
You could go a bit shorter for a shorter archer, shorter draw or lower poundage.
For 32" draw I'd go at least 74" and for 32" heavy weight I go a long as possible.
Del
I never make 'em longer than the stave I have in my hand