I work my bi's along with my back and from every pic ive looked at it shows my bi's get worked with every back excercise. How much bi only isolation do you guys do? I normally just throw in 3 sets of 10 at the preacher curl machine and call it a day after my back stuff but today I decided to grab a couple 20s and do alternating hammer curls until failure. So I tossed in 2 sets of alternating curls for 30 reps at 20lbs. Would you recommend more or less?