You gain faster if you alternate............

Also you don't get stuck at the 70,80 and 90 barrier if you alternate. I like to train with 3/4 people casting the spells on me. The gains are soooo quick its unbelieveable. Its just a list of gains down your screen. To gain on a red, the best way is have a mage with no eval casting para fields and run through them. Thats meant to be quicker than casting on yourself.