What's the Logic Behind Hop Additions?

Ok, so I know that you add your bittering additions at the beginning of the boil, your aroma/flavor hops towards the end of the boil as well as in the dry hop. My question is, what dictates adding hops at 20, 15,10, 5, etc? I know that every passing minute you lose less impact to bitterness while adding additional flavor/taste, but what other logic is there?

I have heard people say that if they are gonna dry hop with something, that they will want to add the same variety in the last stages of the boil, but why? It seems like you could get the flavor and taste by skipping these late additions and just dry hopping, what am i missing?

I have the book Hops and the IPA book, but in all honesty i’m doing my masters and my time is consumed so i’m looking for the quick and easy answer from you guys.

The longer you boil the hops (up to 90 minutes or so) the more bitterness you get.
The aromatics evaporate very quickly, so the less boil the better. And the flavor compuonds are optimized at about 15-20 minutes of boiling.
The different times will get you different ratios of each.

Dryhopping adds fresh hop aroma (along with some flavor and bitterness) to the beer that you can’t get with late additions. While I often dryhop to match the late hops in the boil, it’s also fun to add a whole new dimension to the beer by using something entirely different, especially if you’re making multiple kegs out of one beer.

Will dryhopping fade quicker compared to late additions? I know it’s more aroma than flavor so that flavor addition is important but I’ve been playing around with skipping the 5-0 additions in favor of dryhopping.

I honestly don’t know the answer to this beyond what has already been discussed. All I know is that when I want a hoppy beer I just do 60, 15, 10, 5, 0 and dry hop.

Based on your posts, I thought of another question. Do late addition hops add more or less hop flavor than the dry hop? Based on your responses, it appears as though the logic is that the dry hop primarily adds aroma…

I think there is a bitterness/flavor curve and it woks like a mortgage loan. Every hop addition (payment) after the last adds less bitterness and more hope flavor. Just like a loan has more bitter interest at the beginning. I am guessing that the hop additions at various intervals adds flavor complexity that can be achieved no other way.

One of my favorite beers is DogfIsh Head 60 min which I believe is continually hopped