For the past couple of years, I've adopted the following approach for fingerpicking folk rock/alternative music...
E - pinky finger
B - ring finger
G - middle finger
D - index finger
A - thumb
E - thumb
At this point, I'm super comfortable with using my pinky finger on the E. I personally think that it is the most ergonomic approach since I don't have to move my ring finger to reach the E (although I have to cover two strings with my thumb). I've started reading that the pinky is rarely used in picking. What are the pros/cons to this approach and should I forgo using the pinky in fingerpicking?
As long as you feel comfortable with your pinky in the E string it's ok. As for advantages, you might find it easier to play arpeggios of 5 and 6 strings (since you have almost all strings covered), or as well play different melodies along the strings at the same time. It is not anything you couldn't do with the common finger position on the strings, but it's all a matter of how comfortable you feel. In the list of disadvantages you should consider the fact that the pinky finger is the weakest finger, and it might make a difference on your E string picking strength and/or precision. But again, it all depends on your own preferences. Who knows, maybe you can go further with it and create a new technique!
Hope that helps, this is my very first answer (:
I'm also using my pinky a lot when finger picking. In this way there's not so much difference switching between pure finger picking and hybrid picking. So that's another benefit of this approach. With hybrid picking your index finger is not available, so there it's natural to use the pinky more. Plucking two adjacent strings feels more natural with the middle and ring finger rather than index and middle finger too.
Hard and fast rules will only guide you to what people have found worked for them. There is nothing wrong with changing to suit yourself. The thumb sounds good on the lowest two strings, as that's where the bass line often runs, so a fleshy sound is appropriate.A pattern I sometimes use involves only the top four strings, so I use thumb on 4 and 3, with top two strings being played with m and a usually.The pinky can and should be used - it's waiting for the opportunity ! Yes, it may be a bit weak, but soon it catches up with the others, given that chance.Playing a chord on top four, plucking simultaneously, can ONLY be achieved with all four fingers. Keep going, it's the end product that's more important than how you physically produce it.
If you feel comfortable playing with your little finger, congratulations. You have the advantage. There's absolutely nothing wrong with it. After all, you use your (probably even weaker) left hand pinkie too. And pianists use their every finger.
Most classical guitarists play only with their four or even three first fingers because they find using their whole hand too hard. Basically there's two reasons for that:
Many players hold their plucking hand in a position where it is hard for little finger to reach the strings. Especially if it is relatively short compared to other fingers.
Classical players play mostly without amplification and find it easier to get a loud and fat sound with their strongest fingers.
Years ago I asked my teacher about this and he told that actually you can develop a better control for little finger because it has its own moving muscle unlike middle and ring fingers. He is a musician and not a physician so his explanation should probably be taken with a grain of salt.
I eased into right hand pinky use by playing songs finger-style using a chord-melody approach, mostly with full barre chords but these days adding in lots of "open" cords since I now know more what is where on the neck. It may not have been as quick compared to doing exercises but it was sure more fun.
I always say to people who are debating whether to play with the thumb and two fingers or thumb and three fingers that if they only use two fingers they are only using 75% of their available resources and will get a 75% result. Actually, I never considered using my pinky but by my same logic it is an available resource (although I do plant my pinky alot which gives me more control, especially with dynamics because the anchor gives you leverage without much hand movement). People also say that's wrong but I have been playing long enough to make an experienced educated assessment. I can play without it too.
The only other thing I would add is that you don't have to do either or or forego one for the other. You don't have to choose right from wrong. You can however, and maybe should, ALSO play without it. And ALSO be able to move across all strings with alternating index and middle fingers, classical style. It is ALL useful.
I personally don't but if you are not experiencing and hand pain or tension then go for it, use it to your advantage. In classical guitar the pinky is usually ignored but there is a modern trend started by Eliot Fisk (I think). He recommends using the pinky in the Segovia scale exercises. Even though it isn't used in performance it is believed that practicing to use it helps develop strength and independence of the ring finger. I haven't tried it, I'm happy with the other fingers as is.
I always teach my students to use all five fingers. You learn by assigning a finger to a string, thumb picks up the bass notes on the fifth and sixth. Then enforce the discipline of only playing a note with the finger assigned to that string. It's great for playing arrpeggioed chords and finger style. When you get used to it, you'll find that you always have a finger waiting for a note, without moving around so much. Give it a try. 50 year player. 22 year teacher.