How can I add more columns to the Resource Scheduling screen?
All you need to do is change the number of repetitions shown for each of the repeating fields on this layout. There are a few stacked fields here so you'll want to practice on a copy of the file/layout before doing this for real.
And be sure to check out the video of how best to navigate the calendar's tabs: it is a great introduction to working with these layouts. Calendar Tabs
Note that under the hood our calendar supports 20 columns on this screen without any modification to the underlying code. If you want more than 20 columns to show, you'll need to change 3 things: