The durability of tea leaves in brewing is related to their tenderness and processing method. Tender tea or broken tea brews easily but is not durable. In contrast, coarse, old, and whole tea leaves brew more slowly and are more durable.

Generally, tea can be brewed about three times. The first infusion extracts 50% to 55% of the total soluble substances; the second infusion typically extracts about 30%; the third extracts around 10%; and the fourth only 1% to 3%. From the perspective of nutritional components (such as vitamins and amino acids in tea), about 80% are extracted in the first infusion, about 15% in the second, and almost all are extracted after the third infusion. Therefore, steeping a cup of tea all day quickly depletes its nutrients.

As for the aroma and taste, the first infusion is rich and refreshing; the second infusion is still aromatic but less refreshing than the first; the third infusion has faded in both aroma and taste; and further infusions become tasteless. Generally, black tea, green tea, and floral tea are best brewed up to three times.

Oolong tea, which uses larger leaves and coarser tea, can be brewed more times. Bagged tea made from broken black tea is usually only suitable for a single infusion.

In fact, tea steeped for too long not only fails to provide nutrition but may also be harmful to the body. Prolonged steeping can gradually release some insoluble harmful substances (such as certain trace residual pesticides), which may be detrimental to health. For office workers, the ideal brewing method is to have a fresh cup of tea in the morning and another in the afternoon, ensuring both freshness and aroma while benefiting the body.