I always turn battery saver on all the time even after charging at 100%.

If you are refurbished to Low Power mode, yes it is quite fine to use it at all times.

To turn Low Power Mode on or off, go to Settings > Battery. You can also turn Low Power Mode on and off from Control Centre. Go to Settings > Control Centre > Customise Controls, and then select Low Power Mode to add it to Control Centre.

Use Low Power Mode to save battery life on your iPhone or iPad