Any strong opinions on mixing your own masonry mortar vs using premixed? I'm laying a double wythe wall - one side 6" CMU, the other side IXL giant brick. I've used Sakcrete Type S mortar mix from HD and its working ok. I don't seem to have the plasticity and workable time that I would like but I'm not sure how much incremental advantage I'd get from mixing my own. Is it worth the trouble? If so, any recommendations? I'm building a fairly large wall - 3' high x 80' long.