I've had it go both ways for me. I've had 90+% on normal trees and missed all 4 on more than one occasion (granted it's not common). Conversely, I nailed 4 HQ hits in a row once on an unspoiled node with a 1% chance of success. I've been saying this for a while now, but I'm almost positive there is something more to their gathering probabilities than just a straight % base. I constantly find myself on both sides of the issue; either missing a ton in a row with a high % or hitting a ton/getting HQs with a very low %. While statistically it's possible, these things shouldn't be happening as often as they do.