2001 400ex gearing

Hi everyone, not having an issue (I think) just have a question about my 400ex. I have noticed over the short while I’ve been riding that 5th gear is only marginally higher than 4th gear, to the point where it feels like there should be another gear. Maybe I’m not revving it out enough, and maybe I’m overestimating the 4 wheeler’s capabilities, but it almost seems like my top speed should be higher and my last gear should be longer. Has anyone else with this quad experienced something similar? there is definitely a 5th gear, I counted them today, but I’m just wondering why they’re so close. literally not even a 300rpm difference between the 4th and 5th gears.
thanks for the input everyone.
cheers