Multi-column forms can be very beneficial from a user experience standpoint. One common scenario where multi-column forms come in handy is when you have a form long enough to have a vertical scroll. In this scenario, you can reduce the length of the form and make it more compact by ordering your fields into two or more columns. Similarly, when embedding a long form into a sidebar, it may fit better and reduce vertical scroll if you use a column layout. There's no one-size-fits-all approach to effective form design, which is why it's so important to have different layout options available for different scenarios.