Pathways to Discovery in Astronomy and Astrophysics for the 2020s has recommended a Great Observatory Maturation Program (GOMaP) to invest in co-maturation of mission concepts and technologies to inform an analysis of alternatives study for an ∼6 m off-axis inscribed telescope. The purpose of this telescope is to sample atmospheric spectra of around 25 potentially habitable exoplanets using ultraviolet, visible, and near-infrared wavelengths; it is planned to launch in the early 2040s with a total cost of less than $11B, including 5 years of operation. A historical review of past missions yields basic programmatic lessons learned to be considered as the community prepares to implement the Decadal Vision. First, technology development is critical for enabling missions. The robustness, breadth, and duration of concept/technology co-maturation is important for mission success. Second, NASA has never “exactly” implemented a Decadal mission as it was recommended. Third, all missions have the same basic technology challenges of mass constraints: mechanical and thermal stability to design, building a space telescope that achieves the required on-orbit performance, and verifying and validating that performance by test and model correlation. Finally, Decadal missions require sustained community support.