My raised beds kept drying out until I buried milk jugs with pin holes

Last April I built four cedar raised beds for tomatoes and peppers, and by June the soil was bone dry two inches down even after soaking it every morning. I was losing plants fast, maybe three or four a week, so my neighbor Ruth told me to try the old milk jug trick. I poked tiny holes in the bottoms of eight gallon jugs, buried them up to the neck next to each plant, and filled them twice weekly. That was six weeks ago and I have not lost a single plant since, plus my water bill went from $71 to about $48. The roots grew right up to the jugs, so now I am wondering if anyone has used bigger containers like five gallon buckets for bigger shrubs. How deep do you bury yours, and do the holes ever clog up with our clay soil?