Can I connect input AND output to the vsys?

So, I'm making a digital clock with a pi pico and a 16x2 LCD sceen. I'm reading everywhere that if you're going tp use batteries, you should use the VSYS pin, but my LCD is already connected to it to power it. To me it seems not right to connect both a power IN and a power OUT onto the same pin?

You can supply 5v to VSYS and you can also draw power from the same VSYS. Its called "Kirchhoff's circuit laws" if you wish to learn about current flow in circuits.

awesome, thanks so much!