lee loaders only neck size, so if using cast, be careful how tight it makes the neck.
you may want to dedicate a LL to ONE bullet, by opening up the neck a bit, and opening up the bullet hole.
as for scoops, consitant technique is the key. no different than a powder measure, and lots of competitive shooters use them and don't weigh their loads, once they have developed on. (think "Progressive Press")
as for light loads, once you find a weighed load that shoots well, get the next oversized scoop, and with a heat gun, or careful use of a hot plate, warm the base and gently push it up, making the capacity smaller... then dip a few and weigh them.
after you get it sized right, mark it and put it with the LL and mark the whole info one the case.
also note, the LL loads as listed may be light, but for cast, they "May" be spot on.