I’m not arguing brain n elasticity at all; I don’t think any reasonable person will have any major issues learned multiple systems simultaneously. As I said in an earlier post, it depends on how much time they have to train and how good they want to get at a particular system. Let’s say I can train Monday Wednesday and Friday nights. If I do karate Monday, Judo Wednesday, and boxing Friday, how good will I be at any individual one of those in a year? If I want to get really good at karate, I’d probably be best off training that the 3 nights every week instead of one night a week.
If I’m looking to be the most complete fighter I can be in a year and or complete in MMA in a year, I’d probably be best off doing all 3 simultaneously. I’d most likely benefit from someone who knows how to tie all of those together too.
As for the 2 different teachers, it’s not two entirely different takes on the same system. It’s different ways of communicating the same thing. You and I can both teach Newton’s laws of motion, but we may explain it a bit differently. If we shared a student, some things you might say might click better than some things I’d say and vice versa. My CI and the 2nd in charge are on the same page, but their language during feedback can be different. My CI is more of a big picture and hands off and let me work it out the minor details for myself kind of guy, whereas the other one explains the details more thoroughly and fine tuning kind of guy. I’d be very happy with either one of them as my only teacher, but I’m better off with both of them. Nothing either one has said has ever conflicted with what the other said.