It’s quite fitting that this paper on yeast from the Guiness Brewery uses the t-test from the Guinness Brewery: https://en.wikipedia.org/wiki/Student's_t-test#History
One of those quirky little intersections between mathematics and practical business outcomes.
I assumed you meant the “half pour, sit, half pour, serve” but was wondering if there was perhaps another approach?
Guinness requires a different faucet to most draughts, with a restrictor plate that forms the creamy head. The plastic widget in cans of draught Guinness performs the same function as the restrictor plate.
The purpose of all of this is to replicate the head and mouthfeel of a 'real ale' that has been naturally carbonated and dispensed at atmospheric pressure with a handpump.