I did a 60 minute addition in an “IPA” of sorts last night for the first time in maybe 6 months (and that’s a lot of brews). Been doing my first addition at 30, then one at 10 or 5, then a WP at 180.
My theory is you can get more flavor impact by adding more hops at 30 to hit target bitterness than less hops at 60. There are certain compounds in hops that benefit from being boiled. The 3MH thiol increases during the boil but the difference between 30 and 60 is not very big. So why not at more at 30 to maximize thiol content in the wort? Plus you’re not boiling vegetal material for as long as if you added the hops at FW, 90, 60, etc.
You can also lower your boil pH to extract less bitterness without impacting the flavor/aroma extraction. Great way to add depth of flavor to a beer without adding a ton more bitterness.