I've audited dozens of Shopify stores, and the same problems keep showing up. Here are the three that cost brands the most revenue:

1. Tracking last-click attribution only

If you're only looking at last-click, you're undervaluing the top-of-funnel channels that actually drive awareness. Most brands I audit are over-investing in retargeting and under-investing in prospecting because of this. Set up multi-touch attribution — even a simple linear model is better than last-click.

2. Ignoring post-purchase data

Your job doesn't end at checkout. Average order value, repeat purchase rate, and customer lifetime value tell you whether your acquisition spend actually makes sense. A $50 CAC on a $60 AOV looks bad until you realize those customers come back 4x a year.

3. Looking at ROAS without context

A 3x ROAS on Meta means nothing if your margins are 20%. You need to know your break-even ROAS and optimize toward profit, not revenue. I've seen brands scale campaigns that were actually losing money because they were chasing top-line numbers.

If any of this sounds familiar, that's exactly what we fix at Metric Lab. We run full analytics audits for e-commerce brands and deliver a custom report with the data that actually matters.