I have been on both sides of this — as a disabled veteran who fought my own claim, and as an accredited agent who has fought thousands more. The single biggest predictor of winning is not the strength of the first application. It is persistence.
The first “no” is not the answer
The appeals system exists precisely because first decisions are so often wrong. A denial is a document that tells you what to fix. Veterans who read it that way — and come back with the missing piece — win at far higher rates than those who file once and walk away.
Fight smart, not just hard
Persistence without strategy is just frustration. Persistence aimed at the exact deficiency the VA cited is how claims get overturned. That is the whole reason to have an accredited advocate in your corner: so the fight is targeted, the deadlines are protected, and you are not carrying it alone.