From a miner's perspective, I don't see how 1 block per second is possible: It takes at least 1-2 second to re-initialize the miner and get new work from the network, if new blocks arrive every second, it means the miner would never get ready for the real calculation to take place 
Yep most hardware in use for mining has second to multisecond latencies, not even getting into the latencies of global propagation in a network of decentralized volunteers (rather than trivially coerced corporate interests).But I think if you fixate on one second you're not getting the value of of the paper. Just multiply their numbers by 10 if you find 1 second is a bit outrageous considering the practicalities that their analysis excluded.
I will read the full paper more carefully, just a glance from the paper:
"Practically, individual nodes limited bandwidth imposes an additional constraint on these parameters. If every nodes bandwidth is at least 0.427 MB per second, then the network is able to maintain a rate of 1 blocks per second and b = 320 KB per block, with 10000
transaction hashes per block, achieving a TPS of more than 214.0"
If drop this value from 1 block per second to 1 block per 30 second, then TPS will drop to 7, the same as current design