In CRM you have to option to either create your Invoice / Estimate tempalte from scratch, using HTML or use the Drag & Drop tool. Althoug for many use cases the pre-made tamplates are good enough and easy to configure, there are cases in wich you need more freedom in this process. One specific case that I currently have is that after creating the templates for Estimates and Invocies in Zoho CRM that have been approved by my client, after convincing him to use Zoho Books I am finding dificult to justify that the tamplates will not be the same.