Focus Addiction, when exactly is a focus active? Options

[Moon-Hawk]

Is a spell focus or anchoring focus considered active when it's 'standing by' but not really doing anything? For example, Bob the mage has magic 5. He has a force 4 sustaining focus that has, say, Armor. He has a force 4 specific spell focus for Manabolt, and a force 4 anchoring focus for Treat. If he uses his force 4 spell focus for a Manabolt, then much later in the turn his anchoring focus goes off, was his total active foci used at 12, or was it at 8 twice? (sustaining and specific spell, then later sustaining and anchoring)
ref MitS pg 45-46