About the only way you can control speed in some gnarly glades is to literally scruff of speed whenever you can and if you have to, zing around a tree and face up hill some if you need to.
Glades are my favorite stuff to ride and I've bounced off a ton of trees, it happens....
I've also found a lot of fun in making big zig zags and essentially side hilling back and fourth thru the trees to make a sweet tree run last a lot longer. But that's in really tight trees.... More open trees like aspens or something I like to just fly thru those weaving in and out of them.
But ya, it's all about practice.... I can shred trees with the best of them but you get me on a wide open bowl with bottomless powder and I flail around like an idiot and can't make a good looking line to save my life.
It's because I've got a ton of tree riding experience with not insane deep powder (Colorado resort riding)
Oh I've ripped probably a handful of gloves from having to grab onto tree trunks to help me make a tight turn because I was going to fast
But my smile is from ear to ear when I pop out of those trees
"When I do good, I feel good; when I do bad, I feel bad. Thatís my religion." - Abraham Lincoln
Moral of the story: If your going to rob people, wear a diaper.