You have to skip hitting refresh at xx:00.
The moment your clock (assuming laptop or desktop here) shows 1 second you hit free submission.
That's the way I managed to accelerate like 4 tx Monday to Wednesday, 10 seconds later there was no free spot left!
Now, there's no spot left after only 1 second. I tried submitting the captcha at the exact moment, I tried starting at the exact moment. It's all futile.
What's really annoying is that Viabtc right now helps even with ordinals inscriptions, this guy is taking advantage of this and I assume he is using a bot for it, 30 confirms in one go is impossible for a human
That explains why it's impossible now. The captcha stops humans but not bots.