What really decides whether a project succeeds
The three factors
A goal you can state in a sentence. When everyone knows what winning is, hundreds of small decisions get made right without a meeting.
A short feedback cycle. The shorter the time between a decision and its result, the fewer errors accumulate. That holds in code, in product and in the organization.
Decisiveness. A team with no one to decide gets stuck in consensus, and swaps progress for meetings.
What looks important and matters less
Choice of language or framework, the task-management tool, and the exact methodology. All affect the margins compared to the three factors above.
Closing the loop
Everything you read here returns to the same order: define a problem, test cheaply, measure, and release small. The tools will change; the order will stay.
Going deeper
Ask three questions once a quarter: what's the metric we're chasing, what's the one thing slowing us most, and what have we built that nobody uses. Those three answers, in writing, are worth more than most formal planning processes.