First of all, the problem it’s claiming to solve doesn’t make sense, you’re not going to have enough variation in jugs to have a noticeable variation in the fill height of a gallon. Even if you did, for this solution to work, you’d have to be putting the dimple in it while it’s filled and unsealed, which would be extremely difficult. On top of that, you’d have to vary the depth of each individual dimple for that bottles exact level of fill, adding extra challenge on top. Even if the problem as op describes it was occurring, it would be a fuckload effectively cheaper to just have some jugs look slightly underfilled than add this ridiculous step to the packaging process. Hell, it would be cheaper to go make your jug blowing process more reliable. It just doesn’t add up. I’m not saying op is necessarily lying, they could be misremembering what they learned and be earnest about it. I could still be wrong too, but from what op has conveyed and how I’ve understood it it doesn’t make sense.