Well, the thing about minor schema in particular is, you have to have a pretty good UMD score since, if you fail, you don't just fail to activate it.  The thing goes dormant for 1d6 days.  So if you're really relying on getting that undead bane effect on your bow, and you fail the DC21 check, too bad, so sad, try again next week.<br/><br/>Now, if you could combine Skill Mastery with full ranks and the +2 bonus from having activated the thing once before, you could get it off every time, but for right now?  It's only a 15% chance of getting it to work, so you'd need some major boosts to get it off reliably.