Some people say that on-chain "coincidental transfers" are internal wash trading. I usually don't jump to conspiracy theories right away… first, let's break down the process: Are the same set of addresses sharing a single withdrawal point, is there a fixed time window, is it aggregated first then distributed (like payroll deposits then transferring rent)? Many seemingly mysterious actions are actually just habits to save on transaction fees and avoid congestion, especially recently with testnet incentives and point-earning waves. Everyone is speculating whether the mainnet will issue tokens, and as on-chain traffic gets crowded, the paths look more like an assembly line. As for your question, "Why specifically in the same block"... a half-sentence: because they might just be waiting for those few minutes when gas fees are lower.