I have 8 level 90ies atm, working on 9 and 10 at the same time right now.
Some crazy work to you man, hatts off :-)
I only want the toons for goldmaking purposes and then to be honest you only need level 90 for things such as enchanting and jewelcrafting ( not exactly 90, but you need to kill a lot of mobs to get all recipes ).
To all the people saying "nolifer kkthnxbai" , if you play effecient ( and thats easily possible with that many toons ) then going from 85 to 90 doesnt take more than 12 hours /played *( there are faster ways but some are in the grey area or just exploits ). Some like to do achievements, others put their 3-4 hours outside of raiding they spend of wow on alt leveling.
Is it pretty pointless because you cant gear them all enough before the content becomes irrelevant ? Yes, but thats not the point, the guy is having fun leveling.