The idea for nested scrypt is to keep the duty-cycle of memory-bound to L1 cache near to 100% and it also provides the flexibility to control the duty-cycle of the main memory, i.e. 100% - percentage of the time that the algorithm is memory-bound in L1 cache while not writing out to the main memory. Lowering the latter duty-cycle will increase the execution-time of the hash, yet also lower the individual and society-wide electricity requirements of the coin, because for the same hardware less electricity is consumed.