Topping off the resin tank before each print?

Hello guys, I just want to make sure I am understanding correctly.
Do we have to top off the resin tank before every print (which means you have to have a bottle handy at all times and to some extent some resin goes unused)

If it is a large/difficult print topping off the resin really helps with resin flow.
Most of my prints are easy for it because they are small so I like to keep the level low. For one, that makes mixing the tank easier next time. For two, it makes finding chunks easier. And for three I believe it keeps the resin fresher because unused resin in the tank will get a small amount of UV exposure that compiles as you run the machine more and more.