If you know the Major Pentatonic/Blues Scale, chances are you only know it from a 6th string root, which is fine until you need one from a 5th string root... Here is a great trick to use a chord shape that you probably use all the time, and good old box 1, which you probably know the best, to quickly "see" the Major Pentatonic/Blues sound and grab it right away. As some sidebar fun, I'll pretty much show you how to play "Gimme Three Steps" by Lynyrd Skynyrd because the chord progression lends it

Blue Box Guitar Exercise 1