Gotta be honest here, I getting pretty sick of getting really good battle rewards only to find out they are for a school not my own. I know that you do it for varity and to make the content seem like more, because you want use to go back to the same battle to get what we want but seriously, the drop ratio is WAY off. I never get good gear for my school. Its always some other school. And when I do finally get a drop for my school its some lame piece of equipment that I might have been able to use 25 lvls ago. (No matter my current lvl)
I understand your frustration. Especially higher up the levels the best gear is school only to ensure a wizard with mastery can not be as strong as a wizard who is genuinely that school. It would be quite annoying for a life wizard to be able to get the same stats as a storm wizard but have the advantage of double the health.
There are a couple of things some of us do that reduces the frustration of getting gear for the 'wrong' school, or eventually getting gear only to discover it's not as good as we hoped it would be.
1. Make wizards of other schools. We can have 6 wizards on an account and even if they're still low level, when we get good gear for their school we can pass it to them for later. It's still frustrating not to get the gear for the wizard we're farming on, but it's nice knowing we won't need to farm again when our baby wizards get there. They have their own storage space so we don't have to clutter up our first wizard with off-school drops for subsequent wizards. We can use our 'noob' wizards to fish, pet train, hatch, tend gardens, additional storage....they can be pretty useful even if we don't end up questing them.
2. Check gear online to see if it's worth farming for. Just searching W101 and the name of the boss or dungeon brings up information about the drops available. Or adjusting the search to something like 'W101 best gear sets for storm' brings up some great guides. No-one wants to farm for hours only to find the gear we're in is superior!
NB. When looking at guides check the date it was made as guides chance as new gear/dungeons are added. Try to find the most recent one. If there isn't a recent one, make a post asking for suggestions of great sets for your school and level....wizards love to share the sets they've put together and explain why it suits their game play. It's a great way to see what's available and work out what would suit our own play style best