recreation.gov & Inyo Wilderness Permits ?

i'm trying to get wilderness permits for trips into the east side of the Sierra this August. Permits are handled by recreation.gov. I've reviewed what I can find online, and the most detail I've found is "advance (reserved) permits are available 6 months before date of entry" and are opened at 10 AM ET.

I don't see how this can be valid - at least not precise. How long, exactly, is "6 months"? How many days are in a month? Expecting that this was just a poorly chosen description, through trial-and-error I thought I had determined that it is actually 181 days in advance. However, I'm still finding that sometimes permits appear to be available at 6 AM PT for the "next" day, and other times at 11 AM PT they are still not open. It appears random.

Has anyone been able to deduce how this system works, precisely? I have already missed out on two Sunday entry permits because they were not yet available at 5 AM PT and then after checking back at 6 AM PT they were all gone.

Thanks.