The last block found has absolutely zero impact on the next block found - it's purely luck.

The estimate comes from calculating how often you should statistically find a block based on the current pool hashrate compared to the total global network hashrate. But it is just that, an estimate, not a guarantee.

If you find blocks more often than statistically expected then you're having good luck. Likewise if you find blocks less often than statistically expected, you are having bad luck. Over the long term (>6 months) you should expect to get pretty close to what you statistically expect - that is the good luck and bad luck about even out. Short term it's just luck