Buckshot,
In my book there are times and places for lighter and heavier jig sizes to adapt to. Alot of factors come into play when selecting an appropriate size, depth, current, casting vs vertical, mood ofthe fish, etc… Not to make it sound difficult because it does not have to be whatsoever. When I am casting to shallow water fish, I want this bait in the strike zone as long as possible this time of year. Therefore I go as light as I can and stay with in 6 inches of bottom at all times. There are some days when I am casting to shallow fish in 2-6 foot of water that I have to go so light that I seldom feel the jig hit the bottom other than watching my line slowly go slack. One thing that alot of people forget is that when working these light weight baits is that this should not be used for a search tool to find active fish. This presentation should be used when you have located some active fish and you want to optimize every possible biter out of the school of fish. Basic rule of thumb that I like to do is go heavy enough that you can feel the bottom but yet present the ringworm slow enough to the fish this time of year.
The heavier jig sizes have a place as well. Sometimes vertical jigging 1/4-3/8 oz is needed to maintain bottom contact and stay vertical. I personally like to use a 1/4 or even a 3/8 oz jig size for probing the deeper sides of wingdams. This enables me to stay in the zone without letting the current sweep my jig up and over the wingdam by the current.
Hope this helps a little.
Also, do a search on all the topics discussed here in the last 6 months to a year that pertain to ringworms. Just about every post has a personal preference for selecting the “right” size for the condition you are faced with.