Some general observations (still mulling over these):
Thicker or older leaves are generally more resilient and may steep 6+ times. Examples of this are High Mountain oolongs: FuShouShan, Winter LiShan and DaYuLing. Higher quality Taiwan teas have greater resistance and will steep longer, at least 6 times, some for several days.
Pu'erh sourced from old growth trees more frequently steeps longer and with greater depth. Fermentation may also extend steeping, but it seems to depend more on the source of the tea.
Levels of fermentation, oxidation, roasting may also further contribute to longevity of steeping.
Young delicate greener leaves, like those found in Japanese teas, only steeps well 3-5 times. Shincha and Gyokuro's fine new buds are broken during processing so flavor is extracted very quickly, up front.
A few teas I have steeped for several days, sometimes into a week;
- Origin Tea, 'Hualien Mixiang Red Tea' -small leaves first three, high oxidation/medium roast.
- Essence of Tea, 'Half Hand Made 2014 Rou Gui' Wuyi oolong - high oxidation/medium roast.
- ‘FuShoushan’ - very thick large leaves, low oxidation/low roast.
- Origin, '1995 Mengku Ye-Sheng-Da-Ye' Raw Puerh Cake - aged whole leaves/high fermentation oxidation.
- Floating Leaves, ‘2014 Bai Hao’ PingLin oolong -twisted white tip medium oxidation.
Center; Hualien Mixiang Red Tea's very small oxidized roasted leaves. Upper right; Gyokuro's young leaves broken. Periphery; FuShoushan's very thick large leaves.