Are slow feeder dog bowls actually effective?

Across the reviewers we read, the consensus is that maze-style slow feeders meaningfully extend mealtime for most gulpers, but they are not universal. r/dogs threads repeatedly note that determined fast eaters eventually 'learn' the maze and speed back up, and owners of very large breeds report narrow channels are hard for big snouts. For persistent gulpers, several commenters suggest combining a slow feeder with a lick bowl or scatter feeding.