Unfortunately there is no relation between the pool size and the luck in the direction you want. It's the opposite ...
When the luck increases - more people are joining, but then it should go down to compensate it and it look like the higher hashrate is causing the bad luck, but it is not. If no new miners join the pool a 12h block will actually take 13h
Why 'unfortunately'? Because if it was true, then a solo miner with CPU, would have much more luck and much bigger reward, then no one would need to join a pool at all.
actually not totally true. . luck will change regardless of whether people are joining or leaving. . . agree that higher hash rate is not causing bad luck (or good luck). . . over time "luck" should be 100 over time. . However, when you're talking 6 or so samples per day, its possible to have luck be good or bad and not come back to the average for long periods of time. . . Its not unheard of to have good luck for 25 days or bad luck for 25 days because the sample sizes are too small. ..