For the average team this should happen once or twice a season. Lately i've gotten used to seeing this as much as twice a game.
Conversely, not sure if i've ever seen a punt return for 6, which does occasionally happen in professional leagues.
When I started using overrides for my kickoff team, I stopped seeing this happen against me as often. But my experience may be just anecdotal.
Yes, fortify your gunners and it cuts back drastically on the returns. There's a trap with that but once you gain experience playing you see that the top rated gunners always aren't the best.