However, we can assume it's used:
* Frequently: "Said" is a common word in any language and would likely be used numerous times in a dialogue-heavy film like Braveheart.
* Variously: "Said" is used to attribute speech, and characters in Braveheart engage in a lot of dialogue. It would likely be used to indicate what various characters said, not just William Wallace.
While we can't say for sure how many times it was said, it's safe to say it was likely used many times throughout the film.