There's no need! Because it is fully charged, then your mobile phone battery is full, if you feel that the full charge of the mobile phone can not support your use of the day, you can consider buying a charging bank!
If you feel that the low power mode can meet your day's use, then it is necessary to open the low power mode, after all, it is more convenient to bring a charging bank! I hope my answer can help you, thank you!
There is no need to turn on the low power mode every time the charge is finished, this situation is not necessary, this situation you can turn off, it does not affect the normal use, this situation is designed to save energy and save electricity