When i import an existing form, the complete form will be over written. Is there

In the forms where you have hidden the other sections, is there a scenario when those are ever shown in that particular form? It doesn't make sense to keep the hidden sections in the form if they are never displayed for that task simply because you will show it in a later similar version of the task.

If development time is a concern, then develop the most complex version of the form first (one with the most sections that will be displayed). You can use this as your template for all the other forms and delete the section or change them to be read only as needed.

In the forms where you have hidden the other sections, is there a scenario when those are ever shown in that particular form? It doesn't make sense to keep the hidden sections in the form if they are never displayed for that task simply because you will show it in a later similar version of the task.

If development time is a concern, then develop the most complex version of the form first (one with the most sections that will be displayed). You can use this as your template for all the other forms and delete the section or change them to be read only as needed.