They quit making wood lam limbs for compounds when they started putting out designs that keep the limbs under huge amounts of strain, even at brace height. They found out that wood limbs couldn't stand up to that kind of strain and had problems with breakage. Well, they can't make money if they're constantly doing warranty replacements, so the wood limbs went bye-bye.
Besides, molded fiberglass limbs are cheaper to make anyway, and profit margins increased even further because they didn't reduce the prices of their bows. Then they found out that people would pay even more for a real short bow, so they could charge even MORE money for a bow that only took 2/3rds of the materials it took to make a full size bow....
Woah!!! You verynearly got me all the wayup on that soapbox, Wingbone.

[8D]
Those old wood lam limbs did lose poundage, but only when they were stored improperly. People were too lazy to back off the draw weight when they put them away. I shot my wheelbows all the time and never lost any draw weight with any of them.
I think keeping them in use is the key. If you're using the bow every day, then leave it strung. Like Chad pointed out, stringing and unstringing a recurve is far more dangerous to the bow, because that's where almost all limb twists are caused. However, I don't like leaving an unusedbow strung indefinitely. Maybe it doesn't hurt a thing, as long as the bow is kept out of the heat.I've never tested it.
Old training is hard to shake andit was always pounded intoour mindsto unstring our bows when we were done shooting for the day. I'm already stretching that, because I don't unstring the bow I'm using every day - it still makes me feel kinda guilty though....However, I do switch out my using bows every week or two, so none of them are strung longer than that, at any one time.
Anyway, I think it's best to unstringthe bowif it's going to be several days or longer till you use it again. And use the stringer!