My experience :
1 week ago, I spend 2/3 hours by yew and....nothing but Yew Wood (alot)
Yesterday, same area : found 5 ou 6 Heartwood trees in less than 10 min, and a solo Bloodwood.
Today : I was in need for arrows and collected some wood north of New Heaven. When collecting woods I usually try to "test" as many trees as possible (in case...), and BINGO : a Frostwood tree was waiting for me west from Necromancer's area.
Result : I get 8 x 11 logs (Humain). The less success rate was 2 x 11 Frostwood logs, and the best one was 6 x 11 frostwood logs.
I succed to collect more than 300 Frostwood logs before I loged out. I came back 1 hour later and I was able to collect some more Frostwood before the ressource changed to Bloodwood (on the same tree). Total = 429 frostwods logs (including the +1 log for human).
Then, 3 hours later, it finaly changed to Oak
Am I lucky ? Maybee, as yesterday I additionaly get a Yew and Heartwood fletcher's tool (30 quests olny to get that).