I think PBR answered that simply and best.
Good videos by Eric W. He explains a bunch of stuff.
I myself am NOT a head porter. While I get what is explained to me and have discussions with a head porter (or two) and get what’s being said and explained, I haven’t deep dive into the field. Hanging out with Charlie, he showed me a few things and did some work on a few heads, one port only for me to copy.
Once my garage is up and operating, which isn’t soon enough! LMAO! When ever is something like this done quick enough?
I’ll be setting up a portion in the garage to do minor machine work. Assemble engines, small head work, etc… This is when I’ll start in on head work and porting.
There is a forum Speedtalk where I am at and I read a bunch there. You can find some well known head porters there and pick up from them. But I also find it a little clicky like. They all have their ideas and methods. I don’t think anyone has a head and shoulder way over another.
Really the bottom line no matter what the math says to do is results. The only result worth the salt is actual in car results. Any porter that’s been doing there work for a while will tell you flow benches can be deceiving and/or lie to you.
This is also the reason you have seen me post in a negative manor about calculators and adhering strictly to the math calculations. While math doesn’t lie is everyone favorite thing to say, it’s easy to under perform and possible though hard to out perform a calculator. The calculator is actually incomplete. It’s just the known math.