No pain and guilt here!! Spinning a gear is spinning a gear to me. However, from a pedaling efficiency perspective I do have certain points where I'll change chainrings, That is one of the reasons I enjoy having the gear indicator to help me know when to shift chainrings.
Typically I'll drop down to the 39 or the 34 when I need to go to a gear that is 2 gears below midways. So, I'll usually ride in the middle gear of the range and one below it, but if I need to drop down even further I'll usually go to the lower chainring and then shift up in gears.
The exception is when pulling a group up a "rolling" hill (versus steep hill) using a 50/34. Since the pace line is generally pretty tight and I'm trying to keep the pace brisk and constant, I'll stay in the 50 and continue to shift down as far as the next to the last gear. I don't use the last gear in the big chain ring ever and if I have to be in that easy of a gear I've dropped off the front of the group anyway!!!!