Dense cover as long as it is not a small amount is always good refuge for small fish. The larger amount the better it becomes. Too little dense or more open spaced "fluffy" cover just becomes fish attractors and ambush spots for predators. Keep your true goals in mind when creating cover. Are you trying to catch fish or protect them??
When establishing dense cover as protection areas think of and try to imitate the size and composition of weed beds either dense such as eel grass, milfoil, american and other common pondweeds, or more sparse open area weeds beds such as lily pad stems or bullrush stands. You can't beat the natural refuge areas of weed beds for small fish such as fry to 2" fingerlings.
Stake beds have proven to be good types of cover, but remember the larger the stake bed and more dense the stakes the more it becomes a refuge for small fish and less of an ambush area for predators. The refuge area will be typically shallower and a fish attractor will be located in deeper water. Watch small fish habits they prefer shallower rather than deeper locations.
http://www.crappie.com/crappie/missouri-fishing/105557-stake-beds/https://www.youtube.com/watch?v=uqU5JTkbOTo See this very good article about stake beds.
http://magnoliacrappieclub.com/articles.asp?ID=4
