I trim my own horses. I did it for years on my full size horses and now minis. This in no way makes me an expert. But what I can tell you is that each of my horses has different hoof shapes. Just like people all have different shaped feet. It would be very unfair and I think cruel to try and force a group of people to have the same foot arch and length of toes.
You have to work with the natural shape. Some have longer toes, lower heels, etc. I don't get wrapped up in angles and degrees. I trim the excess, shape what can be shaped moderately, do a mustang roll to prevent cracks and strengthen. A lot of people comment on what great hooves my horses have. I have never had a lame horse or any hoof issues, thrush, etc. knock on wood. IMO people get a little too intense with all the hoof theories and complicated trimming. So much affects hooves, heredity and environment are huge factors.
If you want more details let me know. Like I said I am in no way an expert but I will share any info I have.