you cannot be submitting 8k shares/min - that would suck up too much bandwidth. The whole point to a pool setting a working diff is to keep the bandwidth to a reasonable level. Remember, a pool has hundreds/thousands of miner connected to it and cannot tolerate that kind of data usage from them all.
Heck, at 8k share per connection those large pools will need to spend billions in infrastructure, it is not only the bandwidth, there is a more resource consuming part which is verifying the shares, verifying miner's work/share is the same as verifying a block propagated by another mode.
1- The miner will send a block header containing the Merkle root, previous block hash, timestamp, and nonce.
2-The pool verifies that the Merkle root and other data match the work sent earlier to the miner.
3-The hash of the block header calculated with the nonce is lower than the target/higher than share diff set by pool or not?
If the hash is valid, the share is accepted and the peice of info is recorded somewhere on some database to be used in the payment, if the share is invalid, that info will also be recorded for future reference like hashrate graph on the user's dashboard.
It takes some serious resources to receive, verify and record shares, if every single miner sends 8k shares that is going to suck.