The principles are based on entities being responsible in considering what accountability they may or may not need to comply with. This is strictly based on the unique and specific circumstances of their activities and how they utilize the data they receive.
Each entities principles of compliance will differ according to interpretation and circumstances. The core principle is being able to demonstrate that you are committed to GDPR Compliance and are being proactive in achieving this target, whilst being able to demonstrate it when required.
Taking this approach will direct you in the right direction towards compliance.