While I didn't make this mistake, I could see how it could occur. I have access to a 11x17" printer and was able to make a printout of the foam cutout templates from the digital .pdf files on Van's website. After making sure the templates were the correct size (be sure to print "Actual Size"), I noticed that the paper plans provided by Van's were printed about 95% scale. So, had I used the actual page 09-29 templates as supplied (or a photocopy), the ribs would be too small. So don't assume the paper plans you receive from Van's to have the correct page scaling. Maybe some do, mine didn't.
On another note, in my empennage kit, I was provided 5 PVC foam blocks, 4 were 5.25" long and the 5th was only 4" long. I'm not sure if this is how Van's is supplying these blocks now or if was just unlucky, but after some repositioning, I did manage to get all 3 ribs to fit the 4" block, but it's pretty tight. I used a hot wire to cut these out as I'm not sure a bandsaw would have worked.
On another note, in my empennage kit, I was provided 5 PVC foam blocks, 4 were 5.25" long and the 5th was only 4" long. I'm not sure if this is how Van's is supplying these blocks now or if was just unlucky, but after some repositioning, I did manage to get all 3 ribs to fit the 4" block, but it's pretty tight. I used a hot wire to cut these out as I'm not sure a bandsaw would have worked.