Yup, completely agree. Maxing these options do not always produce the best results. I find that a parallel of 2-3 and a windows size of 256-512 gets me the best consistent results.
I am just thrilled to get over 1Mbps to 12Mbps (by rebooting the Arris modem every other day).
And now with the Netgear modem, getting over 50Mbps. Just thrilled! This was after 1-2 months of frustration, confusion, and despair.