I've been detailing and helping quite a few people over the years.
This is great to get your headlights looking new again, but it's not a long-term solution. You'll be going back to having to polish your headlights at least once a year or worse depending on where you live, how much you drive, etc.
The best solution, after these sanding steps in my opinion, is to add a few layers of clearcoat and then wetsand with 1500 grit and polish. This should eliminate the need to have to revisit this annoying detailing step in the future!