If you're elite, fewer the better. If you're D3 or small college, load up. You only get a small amount of time in your life to compete in the great sport of cross country.
I loved the races in college and we had about six. I always wanted more. My times kept getting better in each race and I never felt burned out. Getting burned out is kind of a big American myth perpetuated by the Bowerman hard/easy obsession. A lot of runners do not get burned out.
Yes, if you're super high level like Rupp, be calculating.
If you're small college, have fun with it and race a lot. When you're in your early 20's, the body recovers pretty quickly. If you're still dead a week after your last race, you're probably not in shape.
However, eight is enough ... sit out one of the races later in the season. Five to seven, sure, what the heck. You have about 11 weekends, with seven racesyou have four weekends off. If your body can't handle four weekends off in three months, something is wrong.