An $11 add-on lifted account-wide EPC 28%

An $11 add-on lifted account-wide EPC 28%
The 24-hour cookie pays on everything in the cart, not just your linked item. A coffee site tested it directly.
Control: link the espresso machine only. Test: link the machine, then suggest beans + descaler + a cleaning kit below.
n=6,300 machine-clickers/30 days.
— Control EPC: $0.44
— Test EPC: $0.56 (+28%)
— Average items per order: 1.3 to 2.1
The machine commission was capped, but the consumables stacked at full rate inside one cart.
So what: your job after the main click is to fill the cart. Every cheap, obvious add-on is incremental commission on a cookie you already paid for.