Migration overrun
Average timeline overrun across our migration work (Magento, BigCommerce, WooCommerce, Neto, OpenCart). The culprit is almost always data — variants that don't map cleanly, redirect lists three times longer than the export suggested. We now build a buffer into every migration quote because pretending it won't happen is worse than planning for reality.
What we changed: a two-day data audit before we send the quote, not after. The quote you see is the actual number, not a hedge against surprises we couldn't be bothered to look for.