Its not as simple as you think. There are VERY good reasons why you do NM + angle (I wrote a long post explain why a while back). I am not going to repeat it all here but basically you do NM + angle because -

1. It is more accurate. A spec of dist/dirt/old oil/nick on the thread or rust in the block will mean that that bolt wont be pulling down as hard even if it is done up to the same torque wrench setting. The error gets much bigger the higher you have your torque wrench set, so at 30nm you might not get any difference at all but at 110nm it will be a big difference. In contrast, angles are always the same. 90 degrees on one bolt will apply the same pressure as any other bolt with the same thread pitch. So NM + angle is more accurate and even.

2. TTY bolts stretch which stuff up the torque wrench setting. It is much easier to over tighten a bolt using a final NM than a NM + angle.