So I am tasked to create a website for a pet club(of course using Odoo)

I've created custom Odoo app, modules , website in developer mode(with little to no python/xml coding.)

but a acquaintance of mine said that after I asked him how to export everything to a custom app(with manifest, init, models,views, etc.)
" You can backup the entire database but there is no way to export an app out of odoo developer mode. You are literally modifying the contents of the database. However I only recommend developer mode or Odoo Studio for prototyping only. When you go to production you really need to create a legit Python module for your modifications. " 

He said that it is advisable to create a custom app(hard code it) from a project management and code management standpoint.

Should I continue do it using Developer mode create/edit modules, views, form etc. or should I scaffold a custom app folder and do it there?