反弹 is not a word you speak without thinking. You shall know what the meaning of 反弹. 反弹 is normally talking about increased transmembrane receptor expression because of blockage of its ligands for quite long, therefore, leading to increased response when normal ligands are present. This is certainly not the case in asprin. Because 50% of platelet die in 5 days and bone marrow will make new platelet. Remember, asprin is not to block platelet numbers, it only affects platelet cyclooxygenase, and bone marrow will not make more or super platelets.

The drug asprin metablizes with platelet, therefore, 5 days (half-life) would give to 50% recovery of platelet function. In fact, this is a report showing that cyclooxygenase activity is increased about 40% in about 5 days after stopping usage of asprin.

therefore, in normal situation 4 days is safe.