Hiking and backpacking is pretty rare in Greece still, so we tend to be a bit of a novelty when we walk through a village in many areas of Greece.
Personally i enjoy the solitude of backpacking so i try and stay high and away from villages, it's extremely difficult to carry enough food for longer trips though.
So villages are an inevitability.
Problem when you start resupplying in smaller villages though is getting high caloric food that's also light weight.
All but the smallest villages have supermarkets these days, so you can stock up on Pita breads, hard cheese's, salami, rice, pasta, condensed milk (Noy noy)
If you can get eggs from a farm then they'll easily last 1 week.
Another option is to use shelters of the various hiking clubs of Greece, if you send them a email then they will usually give you an address for you to mail food to, it'll then usually be waiting for you at the shelter.
With a bit of forethought and planning food isn't a problem, it does necessitate meeting other people though.
As i say by far the biggest problem in Aug and Sept is water.
If your higher than say 1000m there are very very few water sources at that time of year, even larger rivers down in the lower parts are bone dry.
We did a hike around Kalavrita a few weeks back and the water was flowing that hard a fast i literally couldn't hear my friend talking to me even though he was stood right next to me.

We were in the same spot in August last year with my Mrs and that same river was bone dry.
Even well known water sources like Drakolimni are reduced to nothing more than puddles in summer.
Being English water sources have never been a worry for me, i've been caught out a few times here in Greece though by what i thought were certain water sources only to find them bone dry in the summer months.