It seems that most basses have a string to string spacing of about 19mm or 17.5mm, sometimes 16mm at the bridge. Recently, I modified my Squier DAJV bass by adding another string, making the string spacing just under 15mm. I find that this facilitates faster left hand technique. I have always wondered why bassists prefer wide string spacing. I never learned slap technique. I will start slap lessons pretty soon. I occasionally do preliminary thumb exercises, attempting to make my up & down strokes. My up strokes seem to be problematic in that it's hard to stroke "through the string" without abruptly hitting the string above it, whereas I can get a decent up stroke on the low b string with no string above it to impede the flow of the thumb? I have seen Marcus Miller on YouTube videos do lot's of fast thumb work, & I don't see how I can even approach it. In terms of learning slap technique did I make a HUGE mistake shooting for a 15mm spacing. Funk jazz isn't my big priority, my tastes run more in the direction of neo traditional. I'd mostly like to play the sort of stuff that Eddie Gomez & Marc Johnson perform with Eliane Elias (only on electric bass guitar) or the stuff Steve Swallow did with Gary Burton. Playing slap isn't life or death, but as my user name implies, I am intrigued with the Marcus Miller growl & purchased this particular bass (along w/DR strings) to get that cool sound. Did I box myself into a corner shooting for 15mm?