Brandon-
You can pretty much buy ALL your food along the way without too much difficulty if you aren’t picky, however many of the stops near the PCT are expensive and don’t have great selection-this is why maildrops can be popular with some people.
I did all of my maildrops (besides Warner Springs) from the Trail, making pre-hike planning easy. I shipped food to Kennedy Meadows from the Saufleys, sent 3 boxes to Oregon stops from Ashland and sent 2 Washington boxes from Portland. I was able to adjust to my cravings and portion sizes and not ship food across the US. However, putting together 2-3 maildrops can be stressful and will ruin a good zero day.
The longest stretch without resupply is 175miles in the Sierra, but even this isn’t really true, as many (myself included) resupplied in Independence. Your general PCT stretch is usually around 100 miles, or 4-5 days.
I highly recommend Yogi’s handbook, which can be found at Pcthandbook.com It’s the best planning resource out there and Yogi has done a great job on it. A must have.
Feel free to shoot me an email with any questions.
A-Train