Hi Bernardo,
No need for conditionals, since what you describe is pretty much the way repeating groups work by default. See the following example…
The above goes from 4 > 3 > 2 > 1 columns, but it could easily be configured for 3 > 2 > 1.
Currently, we have no explicit control over the breakpoint widths. Rather, the RG’s Min width of column setting is used along with the max width of the RG (or its container) to determine the max number of columns that will display. The number of columns will then automatically change based on how many will “fit” into the current container width.
Of course, with some custom CSS, more layout control is possible, but I’d urge you to keep things as simple as possible.