I believe it doesn't matter that Earlene thinks the Wilton chart is wrong. If you do the math, the numbers don't lie, Wilton is nearly spot on for industry standard 8 cu. in. servings...here's a helpful cakulator (see for yourself; actual volume numbers, not guestimates):http://shinymetalobjects.net/cake/calculator/cakulator.html
I'm not criticizing what you do. You are misleading OP by giving your OPINION about what they should do and making it sound like it's "a must" when there are alternative choices other than your way. It appears OP is very inexperienced and may take all advice literally as the law rather than a suggestion. Future viewers should be aware it's just an opinion.