Hmm that sounds unlikely but I will definitely test it out.
This parameter controls the write queue depth for scan threads. It's only one element that controls total RAM footprint for scans, which would be broken down to these items:
- size of batches (hardcoded here: https://github.com/goatpig/BitcoinArmory/blob/master/cppForSwig/BlockchainScanner.h#L24)
- batch queue depth
- constant overhead from the container objects
- speed at which your system goes through the batches
After a substantial rework of the scanning queu mechanism, this parameter doesn't have much effect on full node scans as they're leaner, nor is it really necessary anymore. It is very significant for supernode however.