12-14-15-17. The farthest a pinky should stretch is to the 16th. The 17 you could drop down to the next highest string, which is 12 (except the b string). The one time you can do this is if the 12-14-15-17 was on the high e string. There is no string for you to drop the 17 down to, so you must play it. One way is to slide the index finger from 12 to 14, 15 with the middle, and 17 with the pinky. This the one you should use the most. Here's an example of a sequence where you might want to stretch the pinky.


i m r m i 1 m r p r i m r m i i i
e:-12h14h15p14p12-12h14h15h17p15-12h14h15p14p12-11-12--


Here's another example of where you might want to stretch again. The melodic minor scale. (use only when playing above the 12th fret)


i r p i r p i i r p
-------------------13-14-16-17---
----------12-14-16---------------
-12-14-15------------------------


Below the 12th fret, melodic minor as a 4 note per scale.


i i m p i i m p
----------------------
-----------7-9-11-12--
--5-7-8-10------------


As you can see it's the same pattern, very easy to play.

4 note per string scales are great for climbing up the fret board. I'm sure you've seen hundred of guys doing solos climbing up the fretboard. This the the way.

Otherwise you should look for a 3 note per string pattern. Especially for little licks, there's no need to drag you hand up and down the fret board or do any unneccessary stretching.

Hope that helps.