How many pentatonic scales should I learn?

Hey if you've learned one position of the pentatonic scale you've learned them all they all have the same position.Another cool sounding scale is the harmonic minor scale gives your playing a kinda spanishy sound.Also if you really wanna mix things up you can look up the japanese scales like the Kumoi,Hirajoshi etc Marty Friedman,Jason Becker,Jeff Loomis all utilize these scales in their playing.You can go to www.ultimateguitar.com all of the scales are listed there in the misc section hope this helps.