What is it with Rolex caliber nos.?

[buddy13]

Is it just me or do rolex try purposely to introduce complexity for nothing..do they purposely try and confuse me ?

For example how did Rolex update the 3135 inside the new DSSD and SUB-C with a new hairspring and still call it a 3135? But update the GMT movement and replace the 3185 with a 3186..or has this movement undergone further transformations rather than only the hairspring?

Am I correct in thinking there are two variants of 3035 movement? The current one powers the Sub ND and Explorer while the other used to be a date movement (replaced by 3135 then) which is an old caliber?!