Interesting thought, but the 1/day comes into play for more than allocating essentia:Emphasis mine. The one time the caster gets to "choose one or more spells [...] to apply the effect of a metamagic feat," he has 5 effective essentia to work with. After that, he can fill the essentia receptacle, but he can't choose the spells.Once per day, you can invest essentia into this feat and choose one or more spells that you know (and have prepared, if you prepare spells) to apply the effect of a metamagic feat that you know.