Dan cong oolong is a moody tea alright. Season's change also changes Dan Cong teas' performance. I find fresher the dan cong is, the better it will taste in Spring, Summer and part of Fall. They hibernate during winter. When spring comes, they bloom again releasing fabulous fragrance and sweet like nectar. Winter is a season for aged or heavily oxidized dan cong or teas that hold the same characteristics.
Cupping through my stocks of dan cong oolong of various harvests, most of which tasted better than I last had it during Fall and Winter.