After over 35 years playing bass I have just recently started having lessons and learning theory. I play with the index finger only plucking the strings and through exercises I am realising that I’ve played 1,2,4 instead of 1,2,3 resulting in finger 3 having to be dragged around like a reluctant slug. The aforementioned exercises are improving my third finger dexterity and I find myself using it more on some of our songs but not always. I think this is the key, especially if you have been playing a while and have settled into your own style, there is a ‘traditional’ way of approaching playing but I’d stop short of calling it ‘correct’ because that implies that people who play like me are ‘incorrect’ rather than just slightly different. I also respectfully disagree with @Chris B that the guys who know music theory and have learnt a good technique will always be better players, they will usually be better players, sure, but not always, one of my favourite bass players, Mick Karn didn’t know any theory at all, even which notes his open strings were, he would bowl into rehearsals, ask the title of the song being worked on and write some of his bass lines solely inspired by the song title, the band would then sometimes have to restructure the entire song around his bass line. This sounds like a drag but imho that’s what makes Japan’s music sound so fresh and interesting becaus it isn’t necessarily structured around a traditional or classical route. I have often played in bands with classically trained musicians who wonder about my choice of notes, the polite ones will say some of my choices are interesting, others say will say wrong, sometimes I am swayed by their arguments, other times I will stick by my decision because it is right to my ear and by ear likes dissonance, granted it isn’t a classically trained ear but sometimes I think that training will filter out some of the more interesting ideas in order to tread the traditional route. I’m waffling, essentially I am now being tutored and I’m finding the tuition extremely helpful but then my tutor is not insisting that I use two finger plucking technique, he is showing me the traditional route but not insisting how I walk it because he realises I already have a style of my own involving technique and choices of note by ear.