If I use Both input systems during development, will the final product work fine?

I'm working on my first game, a 3d third-person iOS/Android game and so far I've been using the new input system. I've tried to find beginner tutorials on creating touch controls using the new input system without much luck. I started going through this tutorial which uses the old system I presume: https://www.youtube.com/watch?v=UCJXgwSnXuU

...and in my settings I had to switch from the new input system to both to get it to work.

I just want to know if it's fine to proceed like this? And if not, where should I look for creating touch controls with the new system?