So yeah, long story short, the ACTUAL question that DisasterWalk didn't want to ask and we had been talking about is basically about focus items. He thinks that smaller focus items naturally have an advantage when it comes to control, whilst I've been using the RPG to explain that larger focus items can basically "fit more magic in them", and as such, a larger focus item specifically made to improve control would be better at it than a small one.
I think the mindset/attitude as well as the level of skill of the practitioner would greatly affect this.
1. There is a WOJ stating that with enough power over magic, you could rewrite reality. We also have examples of big magic being in small items. Like the fallen being bound into coins, for example.
2. You can't do magic you don't believe in. So if you think you cant fit a big spell into a small object, you won't be able to.