Gluttony implies that fixing all dimensions (Scope, resources, cost and quality) of the project at the start. Such situations arise when we want to achieve more than the expected goal, in result quality is affected. It results in impossible schedules and death marches in the end. As we know Project iron triangle between cost, resources and schedule, we need to vary on thing. You can read more from here.
Time Boxing is quite good technique to avoid gluttony, in agile mode, each iteration is time boxed and we are always focus on project velocity and what we can achieve next, after few iterations , we can guess about the project velocity and bug rhythm, knowing this prevents the temptation of over-commit.