
Most people vacuum in a similar fashion, 'rowing' the vacuum cleaner in straight, horizontal lines. But when it comes to carpet, this isn't the most effective technique, as the upright carpet fibers aren't being cleaned from every angle.
Instead, you can clean carpets more thoroughly by vacuuming in a 90-degree cross-hatch pattern. It's one of the major learnings I've gathered from testing the best vacuums for pet hair in a cat and dog shelter.