The setting should be determined during your fitting. You should be able to put it in the bag and play it as delivered from your Titleist retailer. If your swing has or does change a bit then that is a different story!

I tinker with mine all the time.  I stay between a 5-7 hdcp and I believe I hit the driver pretty well.  But, as we all know, it's not our job, we don't get the hours upon hours of practice to maintain top form.  With that, when on the range, if I feel a tweak in fitting is needed, I will do so.  When I bought the 915, I wasn't worried about what shaft was in it, as I had a very nice upgraded aftermarket shaft I was taking out of my 910 to use with it.  So yes, I tuned my with some range time and course time, on my own. If its wet, I will increase loft to help with more carry, and if dry I might lower it for a bit more roll.  Were human, so some days we have a bigger fade, slice or a draw, hook.  Learning on the range and tweaking it, to me is the reason for adjusting a club.  Because, it's not allowed during a round, and if your not dialing it in often, or at least when needed.  Then I think your not enjoying the biggest benefit of having it. 

Thanks to all who relied. I LIKE to tinker and have been tweaking mine on Sundays .

My 915D3 was fit at a neutral setting and I haven't touched it. I'm all about consistency and if you change specifications I believe you're always searching for a swing problem that may or may not be there. I think that a lot of golfers struggle to improve because they change equipment too often.

One of the reasons I like to play Titleist is because of their neutral settings.  I have put many other drivers in the set up position only to see a huge hook face waiting to duck it.  I prefer a square face so that I can work the ball either direction as needed.  So I'm sticking with A1 on both Driver and 3 Wood.