Before investing engineering time, quantify whether a new e-commerce product line is worth testing. 1) Do top-down TAM/SAM/SOM sizing and bottom-up sizing from existing traffic and conversion, explicitly estimating what percentage of users (>20% vs ~5%) will be affected; 2) compute expected incremental revenue and the minimum detectable uplift that makes the test economically viable (include fixed costs and opportunity costs of traffic); 3) propose a test plan: targeting, ramp, KPIs, counter-metrics, and a go/no-go bar; 4) detail how you’d de-risk cannibalization of existing categories and identify leading indicators before revenue shows up; 5) specify what you’d do if short-term engagement drops but long-term retention is likely to improve.