You have unlimited scalability for building table conversions and load scripts because you can assign from one to dozens to hundreds of individual users to perform these activities on their laptops or desktops.
You can also run tests on servers responsible for executing these load script jobs built by the users from their laptops or desktops.
A great practice is to have your migration servers scalable so users who have built the load jobs can schedule them to run using a global calendar.
A major financial and insurance leader utilized 12 contractors to build the load jobs, test them, and save them. When the time came to perform the migration, they had three migration servers and assigned four contractors per server to schedule their migrations. Twelve contractors using three servers allowed them to move millions of tables within six weeks.