Depends on your goals, but for complex checkouts I prefer to have the ability to save step data and apply business logic at each phase of the data capture.
To do that I keep each form separate; the first N-1 forms present their UI, capture and validate data and then store it in the browser’s webStorage.
None of those forms submit the data anywhere, they’re just handled by local custom code.
The last form, N, assembles all of that data into the actual submit to the webhook or Webflow’s default form handler. There you’ll create and populate a lot of hidden fields from your stored data, and send it all at once.
In my implementations, form N is usually just a review step, it displays everything for confirmation before sending.