All I'm trying to say is that there is times when it is appropiate to use a parrallel minor, and times when there is not. For a beginner, a good rule of thumb is to follow the scale that the singer is singing the melody in.
2nd..if there is a minor chord (2,3,0r 6)in the progression, using the parrallel minor again will be tricky. An advanced player could pull this off, but to a novice it will probably seem like an incorrect scale to use.
Take the GnR song November Rain for instance...applying a parrallel minor over top this progression would be impossible for most novice musicians. An advanced player could pull it off...but it would probably sound too jazz/fusion(y) for the average listeners taste. So, therefore it would be innapropiate to use a parallel minor in this specific circumstance.
So, fellow guitarists, when considering the use off a parrallel minor pentatonic for a guitar solo over a major progression take into consideration song style (rock, classic rock, reggae, country, country folk rock {Eagles or Jackson Brown}jazz, R&B, HipHop, etc..), tempo, feel, melody, bass line, etc..
parrallel minor is used a lot in the styles of modern / alternative rock, Blues rock, blues, and Funk.