90% is overkill for camo. You don't need that high of an index to put yourself into an advantageous position to take out guards. The only real time you need an index that high is when guards are on alert, actively looking for you, and are nearby. Normally, anything above 50-60% will do the job.
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"When I was a young man, I had liberty, but I did not see it. I had time, but I did not know it."