If you have a small amount of data, then yes, you can do a Manual Migration yourself with pretty good results. However, once your dataset size exceeds about a thousand objects, the cost, time, and quality of the migration should become a concern. If you plan on performing a Manual Migration yourself, determine your minimum standard for a successful migration and define a plan to make that a reality.
Our standard for a successful file system migration is: all data vaulted + duplicates resolved + resolved references + searchable metadata + correctly configured lifecycle statuses & revisions. Typically manual migrations end one of three ways: 1) the data is simply lost / left behind (the migration is never completed) or 2) the data quality standards are significantly lowered, or 3) outside help is required to complete it.
Cases 1) & 2) hurt the business in the short term and long term. If you want help planning your migration, let us know, our Data Migration Program is designed to help you learn your options.