When we used RR, we focused exclusively on RR and nothing else. At first, I felt like we might “get behind”, but I’m glad I chose to stick it out with RR. Dd has done addition and subtraction. Ds has done multiplication. I will most likely have ds do RR division when he finishes with MUS Delta and before starting Epsilon, just to cement those facts. I’ll have dd do multiplication sometime before/during MUS Gamma. It doesn’t take long, and you can do more than one operation at a time (addition and subtraction, for example) for a child who just needs review or refreshing. Dd was having a lot of trouble with her facts, so we focused on one operation at a time so she could really get it down. I’m happy to say it worked!