"Gradual progression" means a slow but steady movement or advancement. It implies that something is changing or improving over time in a smooth and consistent manner, rather than happening suddenly or abruptly. Full definition
Through the details that you list in your resume, you should try to demonstrate gradual progression in your career. (bestsampleresume.com)
But it is how such overall aims are broken down into goals for certain stages or years that is important in communicating the need for continuity and gradual progression in developing big ideas. (educationbusinessuk.net)
For instance, autonomy - supportive experiences may support children's gradual progression from emergent to conventional reading and writing, whereas controlling experiences may not only limit children's opportunities to read and write emergently but also undermine their motivation to do so. (ciera.org)