I think uchihaMadara was saying this, but I am going to use more words and throw in some other stuff too:
if you were consuming a healthy level of Iodine in your diet like a japanese person eating a lot of seaweed and you were in good health and you did the loading test and you excreted 90%, you are probably getting enough iodine.
but since you are probably are not eating that much seaweed and thus not much Iodine and you are on this forum and you already did the test and you probably have some health issue(s) the chances of you not needing any Iodine is slim to none. So the chances of you excreting the 90% is about nil......assuming your transport is working well.
If your NIS is working well and your organification is working well too maybe you might excrete 70% or 80% or maybe 35%. Then you know you need iodine.
But if your NIS or organification is not functioning well and you can't actually utilize the iodine and get it into your cells, you are going to pee almost all of it out in 24 hours. Thus the 94% number.
This means you need to fix your broken transport system. Vitamin C will fix the NIS which is usually broken from oxidative damage. B2/B3 in higher doses like in ATP Cofactors will help fix the organification problem.
So no, I don't believe you wasted your money at all. You just learned that you need to fix your transport. So make sure you take plenty of Vitamin C, maybe more than 3mg/day if you can tolerate it and get some ATP Cofactors or the equivalent. According to Charles Hakala Iodine by itself will fix these problems, but the C and B2B3 will fix the transport faster. Hakala labs actually does an Iodine serum/saliva ratio test using blood and saliva to test for transport problems. if the ratio is too far off midline in one direction it means NIS problem and too far off in the other and it mean organification problem. If you have both I don't know how that shows itself, but I don't think you need that test anyway.
I personally am a fan of testing for the reason you just discovered. It helps you get clear if you need to fix your transport systems.
however I don't think it makes much sense to retest with an iodine loading test. I think it makes sense to retest your bromide level in about 6 months. Brownstein kept testing his Bromide level and it took 4 years before his went down. I am personally still high at 18 months in. And in my complicated situation and my engineering desire for numbers I like tracking it because it tells me to stay the course with Iodine and not to stop taking it because I am not noticing big changes like some people do right away.
It would have been nice to have a baseline Bromide level with the test you just did, but not a biggie, even if you want to test the bromide later.
And of course all of that said, if you get that you probably need to take iodine for the rest of your life, some folks are totally comfortable without testing and they just go by their symptomology and intuition or muscle testing and they do great.