I understand the point of having a large battery bank but was just wondering how exactly the output of the panels would be used if I run the devices during charging - just if the output will go through the battery bank and its resistance etc before hitting the rest of my devices.
Given that solar panels and similar base-load charging devices (including battery chargers, alternators and the like) produce a maximum amount of current at set times (eg. solar panels at peak of the day; alternators whenever the engine is running) some sort of "accumulator", like a battery, is needed to provide the rest.
If the panels and battery are connected as mitiempo describes, whether the panel or the battery, or both, supplies the end devices will depend upon the conditions at the time: full sun, no sun, fully charged battery, empty battery, too much load, not enough load, ... so there is really no set answer to your question.
The usual way to monitor what is happening at any given time (to measure the "efficiency", if you like) is with a battery monitor
like the Xantrex LinkPro or Victron BMV-600. I'd think that one of these gadgets will answer all your questions directly and would recommend you install one if you haven't already.