Do you aim to keep the brew time around 30sec regardless of shot size? If so, how do you go about that? Do you grind coarser? Tamp less hard?
If i keep my grind settings the same and tamp with (what feels like) the same force, my extraction time takes a lot longer when pulling a double shot (i use 16g) compared to single shot (8g), and using the same ratio.
brew it for 30 seconds. brew it for 45 seconds. brew it for a minute. like the result? congratulations, this is your recipe. always remember the aim for all this - your pleasure of consuming a coffee drink. you are free to drink any mixture you want and noone should affect your choice based on “the recipe”. so forget numbers. trial and error equals best taste.