User blog comment:Lukeatlook/Pyro's Item Overhaul 8 - The Support Project/@comment-7709681-20141221235050/@comment-4813965-20141222002554

It's rare to see a Ryze get out of mana past laning phase, and besides, I'm sick to death of having to take that one single champion into account while balancing mana items. The effect can be limited to 5-10 seconds if Swain gets too big with it. Generally the idea is to allow for clutch plays in edge situations. Picking Sanguine Orb is a choice alternative to Morellonomicon - "I don't plan on using that much mana in lane, but if anything happens, I want to make sure i don't run OOM".

Anyways, we can go back to the subject when we get to the mage itemization.

As for Runestone, a 10% exp buff is just about what old Zilean ultimate gave. You won't get it before level 6, and after that the accelerated leveling isn't as overwhelming. Or so I think.