Have you noticed how many of the notes are two frets apart? That's because there are two repeating step patterns, or intervals, in our five note scale: Whole Step (two frets) and Step-and-One-Half, (three frets.) In D-E-G-A-C-D, there are no half-step intervals, as found in B to C or E to F, the usual half-step intervals. This is something you will come to appreciate, early on. Let's look at intervals in Mode #3. See the E to G and the A to in term C right above it? Those are the step-and-a-half intervals we are now discussing. In time, the player sees the scale in terms of degrees and intervals as much as in terms of notes.

I am a devoted sight reader. Personally, I don't find any substitute. That having been said, sight reading is recognition. A good sight reader can sit down and play from a score he or she has never seen. Today's pentatonic mode player achieves speeds unheard of in traditional music. Pattern playing is largely responsible for that.
As an aside, take a moment to reflect on the way the patterns on the bottom two high strings, B and E, shift to the right on every mode, due to that de-tuned B string.