Hashrate and only hashrate matters for the probability of mining a block.
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[chance with 50 PH/s for 3h] > [chance with 25 PH/s for 6h] > [chance with 5 PH/s for 30h] that is simply because you can remove "for xh".
The more I have dealt with it after your hint, the more clearly I agree with you. You are absolutely right. I have adjusted the original post in this section.
Thank you for your attention and advice.