B**** what?
Luffy says he fought the beasts for two whole years, and that he needed Gear Fourth to do it. [
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Rayleigh mentions Gear Fourth and Kong Gun by name, indicating that Luffy used it on the island, multiple times, since he said he took on the "others" with Gear Fourth[
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]. Others, meaning plural, meaning multiple fights, meaning multiple usages.
Also bear in mind that Rayleigh left the island Luffy was trianing on six months early[
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Now unless you think Luffy developed Gear Fourth, used it on the animals, developed King Kong Gun, and then never used it again for the following six months despite needing it before that AND stating that he fought for two years straight, which is retarded as hell, then he absolutely did use Gear Fourth way more than two times.