WeChat official explanation of message recall mechanism: Text recall within 2 minutes is just right.

On May 22nd, the official WeChat account "WeChat Dispatch" explained the design logic behind the message recall feature on WeChat. WeChat explicitly stated that different types of messages have different time limits for recall: text, voice, image, video messages can be recalled within 2 minutes of sending; while file messages such as Word, Excel, PPT, PDF have a longer recall time limit in hours. The WeChat team explained that although 2 minutes may seem short, it is just right for recalling a message. The basis for the 2-minute limit is that the recipient most likely has not finished reading the message yet, so recalling it is like "rephrasing" and will not interrupt the flow of the conversation; whereas after 2 minutes, the recipient has probably read or even replied, making a recall at that point awkward. The reason for the longer time limit for file messages is because there is a natural "time difference" when the recipient views the filesuch as being in a meeting or commuting, so 3 hours allows for enough buffer. The WeChat team stated that recipients who have had their message recalled need to be reminded because as a communication tool, the primary concern is the accuracy of delivery. If messages can be sent and disappear without a trace, then questions like "Did you receive it?" or "What did you send?" would become an endless abyss of uncertainty.