At small scales it's probably better to spend your time working on the core product than to make small tweaks, but once you're operating at a large scale a 0.1%

At small scales it's probably better to spend your time working on the core product than to make small tweaks, but once you're operating at a large scale a 0.1% conversion bump from a small change (like making the cents display in the price smaller) can mean millions of dollars in increased conversion.