How to: Electrical Wiring Distance & Voltage Drop
The drawing is cut off and we can't see most of the exterior receptacles, but it looks like they're mostly on the far side of the building from the panel (lower left and I really hope the panel isn't outside, that's asking for trouble). 

Your building is EDIT: 54x58, that's 76' on diagonal, plus 10' twice to get to the attic; 96'.  That would be about 5.6% voltage drop at full 20A, or half that at 10A.  If you strictly follow the 3% voltage drop on max current rule, you can only get 51' out of 12AWG... but that's not the rule.  The actual rule is try to stay around 3% for the actual ampacity you expect to use, so for a 12A electric lawnmower you're a tick over 3% for a 96' run.   No big.

Seriously, one guy strictly following the 3% fake-rule was about to install 600kcmil for his 1600' run to a couple of 10-watt post lights.  I showed him how to do it with 14AWG.

Nothing says you must wire in a string all the way around the circumference of the building.  You can wire a separate homerun for each receptacle.  Or more likely, you can wire in a star configuration, or even more than one star. 

For instance as you suggest, I would establish two "stars", one at the panel and one, about I don't know, the kitchen.  I'd take each receptacle to whichever "star" is nearest. In some cases that might end up being a home run to the panel.   

If you have 2 or more homeruns, you can either make them separate circuits or the same circuit, up to you. 

I know some places like the Philippines use 2 breakers per circuit, and panels get pretty crowded pretty fast.  You can get panels with as many as 84 spaces - panel spaces are cheap, buy LOTS of extra.  You can also do sub-panels - that might be a good idea given the size of the house.  If you had a sub-panel in, say, the laundry room, a lot of these concerns would go away.  You'd have to do a load calculation to see how large the subpanel should be, too large is not bad.  It can't exceed the size of the main breaker obviously.