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M_V
No, an iPhone charger is 0,5 amp if I remember correctly. It's the iPad charger that's 1 amp, but that's not relevant to your question.
In reality this means if you plug a battery in that's completely flat it's gonna charge at 5 volt and 1 amp for the first second of charging. It charges at 5 volt 0 amp when the battery is full (cause you can't charge a full battery). And in between your amperage (current) slowly drops, that's why your phone charges pretty quickly to 30%, but the closer you get to 100%, the slower it goes.
When you leave on your lights you are making it harder for yourself, when there is no connection between the 2 leads on your hub there is no current being drawn from your hub, there's only a voltage of 6 volt. Current*voltage=power so when your current is zero the power you need to put into your hub is zero.
When you put a 0,5 amp light on your hub and turn it on, your current is 0,5A and voltage 6V resulting in 3Watt (0,5*6=3) of power it uses, so you'll have to put out 3Watt of extra power through your legs.
Back to the iPhone (or di2) charger, when the battery is fully charged the power going to the battery is zero since there is no current, so leaving it plugged in doesn't result in extra Watts needed from your legs.