Setting intonation is one of the most basic skills any bassist should learn. Take care of this yourself and you'll never have to waste time and money on it again. I check intonation on every bass before a studio session. Even then, I've run into issues in the studio and it was a simple fix that saved the session. This was with a grammy-nominated producer sitting right there, too... Not exactly "low pressure". Took less than a minute and we were on our way.
BTW - his comment after the session was that I was "on par" with Lee Sklar and Neil Stubenhaus (he's worked with both in LA) in regards to tone, preparation, professionalism, and playing. Imagine if I had to cancel the session due to bad intonation?!
Scale, high frets, tuning, etc, have little or nothing to do with it. It's simply the longitudinal placement of the saddles along the string path. If the notes were sharp, the saddles on those strings were too far forward toward the nut - making the string length less than it needed to be. It really is as simple as turning a screw, though it does take a great ear, a HIGHLY accurate tuner, and some finesse. To get the BEST results, it's pretty imperative that the strings are plucked with the same force and in the same orientation as when *you* are playing the bass. That's why it's best if you can do it yourself.
